73 K5 needs a new transmission, no idea what to ask shop for

[rc73]

Hiya. I have a 73 K5 that has a 3 speed auto trans, know next to nothing about transmissions and I need to replace it with something more efficient for freeway speeds. I'm going to go to a transmissions shop, but I don't like going in with zero clue about what I'm asking for. Can you all give me a bit of advice so I don't get my pants pulled down when I start talking to mechanics?

Thanks in advance.

 

[Bent77]

What you’re really looking for is a conversion to transmission with an overdrive, which likely also includes a new transfer case as well as driveshafts

 

[rc73]

What you’re really looking for is a conversion to transmission with an overdrive, which likely also includes a new transfer case as well as driveshafts

Thanks. That gives me an idea of what I'm asking for. Big help.

 

[Bent77]

Thanks. That gives me an idea of what I'm asking for. Big help.

Well, how equipped are you for this? If making it a really good highway vehicle is the plan, it could be very expensive

 

[rc73]

Well, how equipped are you for this? If making it a really good highway vehicle is the plan, it could be very expensive

Financially equipped? I'm in pretty good shape, and I'm expecting it to not be cheap. Are you talking more than $10k expensive? If so, I'm still gonna do it, but I may have to reprioritize some things. But I've had this truck for 30 years and am very determined to still have this thing when I die

 

[Bent77]

Financially equipped? I'm in pretty good shape, and I'm expecting it to not be cheap. Are you talking more than $10k expensive? If so, I'm still gonna do it, but I may have to reprioritize some things. But I've had this truck for 30 years and am very determined to still have this thing when I die

Uh well, I was more asking if you are capable of doing the work. My fear for anyone having a shop do work like this is getting completely cleaned out

I was more curious if you were able to find a donar vehicle and possibly use most of those parts, possibly having some rebuilt if necessary

 

[mechted]

What kind of drivetrain do you currently have? Tire size? Offroad habits/goals?
If you are mostly stock and just want to upgrade to a overdrive, then a 700r4/np208 with driveshafts is probably the cheapest, reliable option
If you are higher modified then going 4l80e and all the mess that entails may be more appropriate

A stock 73k5 probably has a th350 transmission and either a np203 or a np205 transfer case.

 

[rc73]

Uh well, I was more asking if you are capable of doing the work. My fear for anyone having a shop do work like this is getting completely cleaned out

I was more curious if you were able to find a donar vehicle and possibly use most of those parts, possibly having some rebuilt if necessary

I'm not equipped to do the work myself, but I have friends I can go to if necessary. I'm planning on getting quotes from more than one shop, and I'm not in a hurry. But I get where you're going. And I'm not above going with rebuilt.

 

[rc73]

What kind of drivetrain do you currently have? Tire size? Offroad habits/goals?
If you are mostly stock and just want to upgrade to a overdrive, then a 700r4/np208 with driveshafts is probably the cheapest, reliable option
If you are higher modified then going 4l80e and all the mess that entails may be more appropriate

A stock 73k5 probably has a th350 transmission and either a np203 or a np205 transfer case.

I honestly don't know what drivetrain I currently have (bought it in the 90's and I think it was mostly stock mechanically), tires are 35", the only offroad habits I have is in my backyard (4 acres of desert), no goals of any serious offroad use. I used to live in a place that didn't require me to get on the freeway for anything. Everything was withing 15 miles on surface streets. Now I'm in the sticks and would like to be able to take freeways comfortably.

 

[mechted]

Yeah, sounds like you want to do some research on a 700r4/np208 swap. This was the most common drivetrain for K5's in the 80's. The stock 700r4 needs a few upgrades to deal with the 35" tires daily, but should be a straightforward swap.

Best option might be buying a complete setup or a donor vehicle.

 

[Chickntrk]

Define comfortably, I always laugh when I hear people say I’m gonna get overdrive so I’m more comfortable on the highway, realistically you’re going to drop about 500-800 rpm and change nothing else about the vehicle, if doling out a lot of cash for that is worth it to you then by all means, me, if it ain’t broke drive it and enjoy it.

 

[eodcoduto]

Th400 and some 3.55’s. Easy day

 

[rc73]

Yeah, sounds like you want to do some research on a 700r4/np208 swap. This was the most common drivetrain for K5's in the 80's. The stock 700r4 needs a few upgrades to deal with the 35" tires daily, but should be a straightforward swap.

Best option might be buying a complete setup or a donor vehicle.

When you say complete setup, you're referring to trans/drivetrain, yes? And thanks for the help.

 

[rc73]

Define comfortably, I always laugh when I hear people say I’m gonna get overdrive so I’m more comfortable on the highway, realistically you’re going to drop about 500-800 rpm and change nothing else about the vehicle, if doling out a lot of cash for that is worth it to you then by all means, me, if it ain’t broke drive it and enjoy it.

Good tip. I wasn't expecting a huge drop in RPM, but this is good to keep in mind when weighing the cost.

 

[mechted]

When you say complete setup, you're referring to trans/drivetrain, yes? And thanks for the help.

Transmission, adapter, Transfer case, Crossmember, driveshafts. T-case shifter, TV cable,.... probably a few other bits. Probably looking at $3k-$6k for parts alone, plus labor to install.

Or you could probably have your current trans rebuilt for $2k? (random guess- it varies by shop and location)
The whole cost benefit thing will never favor a transmission swap unless you have the parts for next to nothing and you install yourself. But that's not always why we do these things.

 

[rc73]

Transmission, adapter, Transfer case, Crossmember, driveshafts. T-case shifter, TV cable,.... probably a few other bits. Probably looking at $3k-$6k for parts alone, plus labor to install.

Or you could probably have your current trans rebuilt for $2k? (random guess- it varies by shop and location)
The whole cost benefit thing will never favor a transmission swap unless you have the parts for next to nothing and you install yourself. But that's not always why we do these things.

Gotcha. Really appreciate the advice!

 

[rc73]

And thanks to everyone commenting for not pointing and laughing (out loud) at the newb.

 

[HankScorpio]

The $10k price was actually what came to mind when you first posted. A rebuilt trans, trans core, rebuilt t-case, core, some driveshafts, crossmember mods, a shop competent AND willing to take on the project could be hard to find.
I am often surprised when I talk to 40hr a week mechanics, they are not actually encyclopedias of swap knowledge. In fact the new guys can't work on carburetors any more. Finding someone who truly understands what your goals are and how to achieve it will probably take more of an off road or hot rod shop than just a transmission guy. I am interested to hear what you find from mechanics.

 

[eodcoduto]

The $10k price was actually what came to mind when you first posted. A rebuilt trans, trans core, rebuilt t-case, core, some driveshafts, crossmember mods, a shop competent AND willing to take on the project could be hard to find.
I am often surprised when I talk to 40hr a week mechanics, they are not actually encyclopedias of swap knowledge. In fact the new guys can't work on carburetors any more. Finding someone who truly understands what your goals are and how to achieve it will probably take more of an off road or hot rod shop than just a transmission guy. I am interested to hear what you find from mechanics.

You have to figure the last year GM used a carb was 1986-87? So 37 years ago, its hard to find anyone under 40 years old that knows how to tune a carb.

 

[rc73]

The $10k price was actually what came to mind when you first posted. A rebuilt trans, trans core, rebuilt t-case, core, some driveshafts, crossmember mods, a shop competent AND willing to take on the project could be hard to find.
I am often surprised when I talk to 40hr a week mechanics, they are not actually encyclopedias of swap knowledge. In fact the new guys can't work on carburetors any more. Finding someone who truly understands what your goals are and how to achieve it will probably take more of an off road or hot rod shop than just a transmission guy. I am interested to hear what you find from mechanics.

I was prepared for $10k, so anything under is gravy. I'll post an update when start talking to shops. There are quite a few offroad shops in LA county, so I will hit them up first.