4x4 trans swap th350 to 700r4
 

I have a 76 4x4 with a tired th350 & 203 transfer case and i would like to swap a 700r4 in. what will i need?

Re: 4x4 trans swap th350 to 700r4
 

A heavy duty built 700R and converter for starters. Personally i would swap out for a th 400 for less money. It will last longer and give you less problems. Or the th 350 can be built to handle alot of stress also. I have a 700R in my garage that came out of an 86 Z-28. But i will probably give it away. The only overdrive i will use for HD purposes is a 4L80E or a gear vendors setup. Both are out of my price range.

Re: 4x4 trans swap th350 to 700r4
 

Welcome to the board,

Tell us about your truck and its intended usage.

The durability of the 700r4 tends to spark debate. A stocker behind a torquey big block and heavy foot is not going to last especially if you tow heavy loads, run big tires, and use high gearing. They can be built to last but it can get pricey and finding a competent builder who knows the weak points and how to build them can be tough to find.

If you were to switch to the 700r4 either get the np208 transfer case that comes with it or adapt to the np205. No sense staying with the np203.

This all tends to add up $$ so do your homework. Good luck.

-steve

Re: 4x4 trans swap th350 to 700r4
 

snj8198
the truck will used for the winter, road driven by me or the wife when the county trucks don't plow, small block with minor modifications, nothing more then 400hp. chnage from full time to part time 4x4, restore the body. tire size nothing larger then 35inches dia. posi diffs, not sure which gears but trying to get more mpg, no towing.

Re: 4x4 trans swap th350 to 700r4
 

karl
I agree that the th400 would be the quickest/easist swap and be almost indestructable, however i'm really looking for that 4th gear to help improve my mpg hopefully above 15 depending on tire height/gear ratio of course. The4L80E is a great choice but correct me if i'm wrong won't i need a stand alone computer to manage the shift points? Can i hook up a np205? or will i need to go to something newer? If it needs a stand alone computer what does it take to program and more importantly maintain. thats why i was thinking 700r4. who would you recommend for the computer?

Re: 4x4 trans swap th350 to 700r4
 

Not be a downer bud, if you're looking for decent mpg you'll never get it pushing 35's. But if you are looking to cruise in OD with 35's you'll want to run 4.56's with your mild small block. All this is not fuel friendly. :)

yes you can adapt an np205 to a 700r4. There is a few write ups on the forum. Give a quick search and you'll find what output shaft you'll need as well as adapter too.