72 K5 Blazer 700r4 upgrade

[Wes Harden]

Since you have a 4l60e and an aluminum t case. If trans is a 4l60e there won't be a tv cable, it needs an electronic controller. If you do have a tv cable trans is not electronic and can be made to work with a reg carb.
There is probably only the factory adapter between the 2. This set up would be 1 3/4" longer in the trans, and not how much longer for the t case with slip yoke. There are at least 3 cross members, I believe the one you want is shaped like a W.
With either the np208 or np241 you will have much better drive shaft clearance.

 

[6872xtc]

There is a difference between a 4L60E and a 4L60, which is just a renamed 700R4.
Electrical plug for an "E" version is on the passenger side of the case on all of the ones I have seen. 700R4 had a 4 pin TCC plug on the driver side rear, above the pan. Only 1 or 2 wires needed for the TCC, depending upon if it's grounded internally or not.

 

[r3bartl]

The t cases start from the factory with a tag on them. Originally that truck was a NP203 (probably since it was an automatic)

The NP203 is an all iron t case

Originally, a NP241 would have been married to that 700r4 (maybe a NP208, but those two are almost interchangeable) this is probably what you have

That will give you some numbers to look up in google photo until you find a tag or can post pictures



The factory automatic in 1977 would have been a 3 speed automatic. If the shifter is the column shifter, it’s likely you are pulling the transmission into 3rd, thus locking it out of 4th - OD



1- the ORD shifter is great. It’s not free, but works awesome. The 208/241 shifter will be a cable driven unit, also available is a JB conversions unit

2- finding a crossmember from a newer application that had the 700/241 application may be the ticket, or build your own…

3- the switch you are think of is probably for the torque converter lockup. It will lock/unlock depending on speed or throttle. You can also run it as a toggle, but I would recommend a vacuum operated switch


Lastly…
Does the aluminum t case have a place for a cable, or is it an electric connection the the output (for the speedo)?

Once you figure some of these issues, you can approach the driveshaft resolution. There may be a junkyard nearby that you can source and original driveshaft instead of popping for a new one


Welcome to the board! Looks like you got yourself some work to do!

Thanks for the write up. I got lots to look into now. And atleast I won't need a twin stick and it should be an easier fix. Just got to figure out this cross member.

Definitely lots of work to do lol when I can post pictures you'll see how much haha.

 

[r3bartl]

There is a difference between a 4L60E and a 4L60, which is just a renamed 700R4.
Electrical plug for an "E" version is on the passenger side of the case on all of the ones I have seen. 700R4 had a 4 pin TCC plug on the driver side rear, above the pan. Only 1 or 2 wires needed for the TCC, depending upon if it's grounded internally or not.

It has a four pin connector on the driver side at the end of the transmission. There's currently nothing plugged into it. I can see it when I have the tunnel cover removed.

 

[r3bartl]

Since you have a 4l60e and an aluminum t case. If trans is a 4l60e there won't be a tv cable, it needs an electronic controller. If you do have a tv cable trans is not electronic and can be made to work with a reg carb.
There is probably only the factory adapter between the 2. This set up would be 1 3/4" longer in the trans, and not how much longer for the t case with slip yoke. There are at least 3 cross members, I believe the one you want is shaped like a W.
With either the np208 or np241 you will have much better drive shaft clearance.

Do we know what years and models the w cross member was in? Or was that dependent on the drive line that was in the vehicle.

 

[Wes Harden]

Most pre 80 k trucks had the flat, 81 up could have any of the 3. Depends on drive line and gvwr

 

[r3bartl]

Most pre 80 k trucks had the flat, 81 up could have any of the 3. Depends on drive line and gvwr

Let the hunt begin lol

 

[Wes Harden]

Not saying buy these but this page has the 2 styles for later k trucks. I am not sure what dictates which is used for which system.

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[6872xtc]

Do we know what years and models the w cross member was in? Or was that dependent on the drive line that was in the vehicle.

The crossmember will also depend upon which height of transmission to T case adapter you have. I seem to recall that there was a 1st generation NP208 adapter that has a tall foot. It used a flatter crossmember.
Then they went to a shorter foot with the S and W crossmembers.
I would have to dig around to verify this and measurements.


With nothing plugged into the transmission, you can either find a plug to wire in a test circuit or drive it to confirm if it has TCC internally. BUT! You need to check TV cable adjustment beforehand. As it sounds like the previous owner didn't finish several things, so I would verify most everything.

 

[Wes Harden]

Yes the TV cable adjustment is the most important thing that keeps a 700r4/4l60 alive, next is keeping them cool. There is no such thing as to big of external cooler for these.

 

[r3bartl]

The crossmember will also depend upon which height of transmission to T case adapter you have. I seem to recall that there was a 1st generation NP208 adapter that has a tall foot. It used a flatter crossmember.
Then they went to a shorter foot with the S and W crossmembers.
I would have to dig around to verify this and measurements.


With nothing plugged into the transmission, you can either find a plug to wire in a test circuit or drive it to confirm if it has TCC internally. BUT! You need to check TV cable adjustment beforehand. As it sounds like the previous owner didn't finish several things, so I would verify most everything.

I should soon be able to post pictures. But the adapter has a very tall foot. So I would assume it would be that one.

Once the rear driveshaft is back in place I'll start with the TV cable first. There's lots of unfinished work in this truck. Lol. It'll keep me busy for the summer and fall. I appreciate all the help.

 

[r3bartl]

Yes the TV cable adjustment is the most important thing that keeps a 700r4/4l60 alive, next is keeping them cool. There is no such thing as to big of external cooler for these.

I'll add that to the list of things I need. She didn't even have a fan shroud for the radiator. So I think she spent a lot of her life running hot lol.

 

[tarussell]

The crossmember will also depend upon which height of transmission to T case adapter you have. I seem to recall that there was a 1st generation NP208 adapter that has a tall foot. It used a flatter crossmember.
Then they went to a shorter foot with the S and W crossmembers.
I would have to dig around to verify this and measurements.


With nothing plugged into the transmission, you can either find a plug to wire in a test circuit or drive it to confirm if it has TCC internally. BUT! You need to check TV cable adjustment beforehand. As it sounds like the previous owner didn't finish several things, so I would verify most everything.

Assuming you do have a short-foot mount adapter ( pics will verify ) and 208/241 case the 85~91 “W” style crossmember from an K5,K10 or K20 ( note the 87+ are called V instead of K ).
The flatter long foot style ended in 1984.
The S style should only fit the 85+ 1-Tons - the odd shape was for clearance for a PTO drive off of the 205 case and are made to fit the deeper frame rails of a 30 series chassis.
If there was a short foot S crossmember for the K5’s,10’s & 20 I’ve never run across one but most likely someone will let us know if there was one.

Note: all the CUCV military trucks should still use the flatter long foot crossmembers no matter the year due to Uncle Sam requiring common parts replacement for the 84~88 run of those trucks so source yours from a civilian truck.

 

[r3bartl]

The t cases start from the factory with a tag on them. Originally that truck was a NP203 (probably since it was an automatic)

The NP203 is an all iron t case

Originally, a NP241 would have been married to that 700r4 (maybe a NP208, but those two are almost interchangeable) this is probably what you have

That will give you some numbers to look up in google photo until you find a tag or can post pictures



The factory automatic in 1977 would have been a 3 speed automatic. If the shifter is the column shifter, it’s likely you are pulling the transmission into 3rd, thus locking it out of 4th - OD



1- the ORD shifter is great. It’s not free, but works awesome. The 208/241 shifter will be a cable driven unit, also available is a JB conversions unit

2- finding a crossmember from a newer application that had the 700/241 application may be the ticket, or build your own…

3- the switch you are think of is probably for the torque converter lockup. It will lock/unlock depending on speed or throttle. You can also run it as a toggle, but I would recommend a vacuum operated switch


Lastly…
Does the aluminum t case have a place for a cable, or is it an electric connection the the output (for the speedo)?

Once you figure some of these issues, you can approach the driveshaft resolution. There may be a junkyard nearby that you can source and original driveshaft instead of popping for a new one


Welcome to the board! Looks like you got yourself some work to do!

Ok i learned some things lol.

1. I have a 700r4 not a 4L60 or 4L60E. the bellhousing is apart of the body of the transmissions. the 4L60s had removable ones.

2. I have a NP208 transfer case on a tall foot adaptor with a u shaped cross member. casting number C15085. The T case has a place for the speedometer cable. now the original one cant reach it but I know you can buy longer ones. Does the 208 have the same end connection as the trucks original unit? It was a turbo 350 and a NP203.

3. I have the shifter for the 208 so i'm going to fab it to the transmission tunnel and i picked up some linkages and it should work perfect.

4. I like the idea of the vacuum operated switch for the torque lock up. got to look into that.

5. with the 700r4 being a mechanical linkage to the column. will overdrive function as it should?

Slow and steady lol

 

[Bent77]

Well that’s some progress.

The column shift “may” work, but it have to be set up off by one gear, so that the lowest gear 1 on the column could be gear 2 in the trans. No guarantee that would work

 

[tarussell]

Ok i learned some things lol.

1. I have a 700r4 not a 4L60 or 4L60E. the bellhousing is apart of the body of the transmissions. the 4L60s had removable ones.

2. I have a NP208 transfer case on a tall foot adaptor with a u shaped cross member. casting number C15085. The T case has a place for the speedometer cable. now the original one cant reach it but I know you can buy longer ones. Does the 208 have the same end connection as the trucks original unit? It was a turbo 350 and a NP203.

3. I have the shifter for the 208 so i'm going to fab it to the transmission tunnel and i picked up some linkages and it should work perfect.

4. I like the idea of the vacuum operated switch for the torque lock up. got to look into that.

5. with the 700r4 being a mechanical linkage to the column. will overdrive function as it should?

Slow and steady lol

More than likely you do have a TH700R4 if it came mated to the 208 but just to keep good information on these threads a 4L60E also came with the bell casted into the case just like a regular ole TH700R4 did until 1996.

 

[Wes Harden]

I have the stock column using a 700r4. Need to adjust the linkage at the bell crank to get the correct range of travel. I can not select manual low only manual 2nd. 4th gear works just fine.

https://www.summitracing.com/parts/prf-60109 This will control the torque converter lock up (TCC) with out having a computer or vehicle speed sensor (VSS)
If you get this kit ditch the crappy cork gasket and invest in a Lube Locker gasket

Pardon Our Interruption

www.summitracing.com

disclosure Summit doesn't pay me for linking them

We need to know what carb you have so we can help you get the TV cable adjustment right. I had a difficult time getting my TV cable adjusted correctly, and able to get wide open throttle at the same time. I ended up using ATP Y-228 cable, Sonnax cable end spring, and tv cable bracket that I can't recall atm. All for a Quadrajet carb, factory style.

 

[6872xtc]

It's possible to modify the bellcrank, (pivot lever) to get all of the gears with the 3 speed column. I have drilled a new hole for the linkage in closer to the pivot. Just enough to keep the original and the new hole from connecting. HOWEVER! That piece is apparently hardened a fair bit. I had to heat it up, then drill it with a good bit of oil.
It would be best to find the column and everything from a truck that was originally equipped with the 700R4. But not required.

It is a trick to get Park function, reverse lights and neutral start adjustments done decently with modified parts, but it can be done. I did it on my '72 C10 and have seen it on a few others.

 

[imiceman44]

Well that’s some progress.

The column shift “may” work, but it have to be set up off by one gear, so that the lowest gear 1 on the column could be gear 2 in the trans. No guarantee that would work

That's how I did the last one, but there is a modification that you can do the the column to get the full range.
I just didn't have the patience.

 

[r3bartl]

I have the stock column using a 700r4. Need to adjust the linkage at the bell crank to get the correct range of travel. I can not select manual low only manual 2nd. 4th gear works just fine.

https://www.summitracing.com/parts/prf-60109 This will control the torque converter lock up (TCC) with out having a computer or vehicle speed sensor (VSS)
If you get this kit ditch the crappy cork gasket and invest in a Lube Locker gasket

Pardon Our Interruption

www.summitracing.com

disclosure Summit doesn't pay me for linking them

We need to know what carb you have so we can help you get the TV cable adjustment right. I had a difficult time getting my TV cable adjusted correctly, and able to get wide open throttle at the same time. I ended up using ATP Y-228 cable, Sonnax cable end spring, and tv cable bracket that I can't recall atm. All for a Quadrajet carb, factory style.

I think this might be my case as well. I have park and on the column it's well to the left of park lol. I might just not have the last low gear. Which for now I'm ok with. Long as OD works.

That locking kit is Exactly what I'm looking for. I'm changing all the fluids and have to take the transmission pan off anyways so it'll be a good time to put that in.

Funny thing is summit is still cheaper than most places even in Canada. With taxes duty and shipping included lol.

So the TV cable. I'm pretty sure it's the original carb that came with the 400. I'll have to do a little digging just to verify but it's nothing fancy like a holly or edlebrock.