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Help! 700r4 to Dana 20...How To articles?

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ArchLAB

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Hi. I am having a real hard time getting a definitive guide to swapping in 700r4 to a 1969-72 Blazer. There is so much contradictory info 'out there'.

Does anyone have a good, step-by-step Post or guide for swapping in the 700r4?

Also, my T-Case is a Dana 20. Anybody have experience adapting onto this onto the 700r4....for less than $600 (Novak)?

Than, in advance!
 
ArchLAB said:
Hi. I am having a real hard time getting a definitive guide to swapping in 700r4 to a 1969-72 Blazer. There is so much contradictory info 'out there'.

Does anyone have a good, step-by-step Post or guide for swapping in the 700r4?

Also, my T-Case is a Dana 20. Anybody have experience adapting onto this onto the 700r4....for less than $600 (Novak)?

Than, in advance!
Click to expand...
There's plenty of passenger side drop t cases that bolt up to the 700, I'd change the case with the tranny.

I'm not much help on the auto swap though
 
"There's plenty of passenger side drop t cases that bolt up to the 700, I'd change the case with the tranny"

I'm coming to that conclusion: Thinking that a 700r4 w/ a NP241 combo is less troublesome. Am I correct in recalling that combo boltsright up w/out an adapter kit?

Maybe there are other combos that are as simple(r)? 700r4/ Np208?, perhaps?

Then I could just sell the Dana, most likely to a Jeep guy.

BTW - THANX!
 
Last edited:
ArchLAB said:
"There's plenty of passenger side drop t cases that bolt up to the 700, I'd change the case with the tranny"

I'm coming to that conclusion: Thinking that a 700r4 w/ a NP241 combo is less troublesome. Am I correct in recalling that combo boltsright up w/out an adapter kit?

Maybe there are other combos that are as simple(r)? 700r4/ Np208?, perhaps?

Then I could just sell the Dana, most likely to a Jeep guy.

BTW - THANX!
Click to expand...
This might help
https://ck5.com/forums/resources/k5-blazer-specifications-1980-1991.8/

There might be a few takers on the D20. Probably not too desirable since the Heeps are backwards side pumpkin. But the gears set might be worth for them
 
That set of specs gives me good info- now I at least know the direct bolt-ons. I'm new to the Blazer game, so I really appreciate the help.
 
FWIW, the Engin'es a 400cu mated to (what seems to be) a 3-speed Saginaw. So, you can see my desire to get those extra gears for a better variety of driving. Not tomention, the strength of a Saginaw in a Blazer is questionable, I Suppose.
 
I put a 205 behind the 700R4 in my '70 truck because I bought into the hype of everyone needs a 205...
And it needed adapted to fit.

We put a 241 in my son's '72 truck and the case won't clear the floor in stock form. The planetary reduction makes the front of the case larger.

Either way, you will have to make changes to the transfer case shifter.
 
GM only had that 3 speed & Dana 20 in trucks for a few years,'68-72 models are what the few I saw were in factory,not sure if they ever had that in a square body truck..they had a weird shifter arrangement and were pretty uncommon,so there may be a market for one ,someone who has a truck equipped that way,will have a hard time locating a good one..the saginaw 3 speeds were not that weak either..

We had one '68 GMC 3/4 ton with a 307 & 3 speed Dana 20 at the junkyard,and it got a lot of abuse,we never broke it..one day the rear axle bearings decided to rust together or weld after they ran dry,we tried moving the truck by revving it full throttle and dumping the clutch--it twisted the driveshaft up like macaroni,never hurt the transmission..truck never moved again,someone bought the engine & drive train shortly after that....
 
700r4/np241SYE is gonna be the best/easist /lightest weight /shortest swap..that will get you overdrive and a great 4lo ratio....try to find a np241 out of a dodge if you can. They have a SYE from the factory. If not then put a slip yoke eliminator on whatever np241 you end up with and bolt it to the 700r4. I'd massage the floor to fit.. The np241 has a better crawl gear than the np208 and they dont make SYE for np208s. The slip yoke is the bane of all things holy and a direct invention from the prince of darkness himself. When the seals on the slip yoke go bad it will suck fluid out of the 700r4, overfill the transfer case till it blows a seal..you will think its a just a leaky transfer case and continue to drive to blazer bash until your 700r4 blows up..then you will spend 2 days in Walla Walla WA.waiting on parts....Oh sorry got side tracked there for a second..... any 700R4 will bolt right up to a np208/np241. the mounts are the same for both...Also dont forget about the TV cable on the 700r4.
 
Something else, I would say that no matter what anyone may tell you, get the TV cable kit from Bowtie Overdrives to match the carburetor on your truck. It makes a big difference.
I say this assuming that you still have a carb...
 
Hi again, Everyone. I'm glad I posted on this Forum - very useful insights. From some of the comments, I'm reconsidering the 700r4 route & may just want to stick with Saginaw since everything's already setup for the Sag/Dana20.

One difference, though: The idea of a Saginaw 4-Speed has gotten my interest. Looks like a straight swap for my 3-speed. Nonetheless, I do have some things to consider:
1) Is there a rebuild for the Sag4 which would beef it up (HiPo/HD)/ optimize the gearing for mostly city/highway but about 10-20% off-roading (mild-medium)?

2) I have a Hurst Shifter for the Sag3. Do any of you know if that works fine with the 4-speed? It looks like if would, as the shifting rods/linkage appears to be the same for the Sag3 & Sag4.

The Sag4 ain't an Overdrive, but it might be better for 'modern' driving than the Sag3.
Thanx again, in advance for any info.
 
There has to be a 465/205 out there for cheap
 
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