700r4 to a th350?
 

This morning I broke the 700r4 in my 1986 swb c10. I'm on a tight budget so I'm trying to figure out what to do. I have a good th350 in the garage, what needs to be done to swap the th350 in?

Re: 700r4 to a th350?
 

I suspect the th350 is shorter than a 700r4 so you might need a longer driveshaft in the back. Might also need a shorter front driveshaft if your truck is 4x4.

Re: 700r4 to a th350?
 

Drive shaft length and front yoke for sure will need to change, probably the throttle bracket to handle the T350 kickdown cable. You may need to drill holes to move the trans bracket. Not sure if the holes are there for both positions of the tranny support. I do not remember if the shift linkage changes between the two or not.

Re: 700r4 to a th350?
 

Measure the transmissions. Long shaft 350's are supposed to be close enough to 700R4's that I heard it can work.

But if you have to build your 700. Go to the wrecking yard, and get a LS 4L65E, and use it's internals. Along with Corvette servo's. This would be about the strongest budget friendly build you can get done.

I would consider rebuilding the 700r4 since with out overdrive you mog may go down a bit, and getting a driveshaft plus other parts your almost 1/2 way to a rebuild.

Re: 700r4 to a th350?
 

Gong from a 700R4 to a TH350 you'll have to move the existing cross member forward 3/4 inch. If the tailshaft and housing on the 350 are 9 inches your fine, it's actually 1/2 inch longer than the 700R4. The 350 uses the same detent bracket on the carb, different cable though. Cooling lines go in the same position, and are the same size. Be sure to wrap and seal the wiring harness for the 700R4 and tuck it along the inside of the frame rail with the rest of the wiring harness just in case you change your mind later.
I just changed mine back to a 700R4, so i just went through what your doing in reverse.

Re: 700r4 to a th350?
 

And you will need some vacuum to the 350.

Re: 700r4 to a th350?
 

Thanks guys,

I broke the sunshell because I have no reverse, second or fourth

I got one rebuild estimate so far of $1500-1800. Gotta price out everything else

Re: 700r4 to a th350?
 

Having done this;
Long (9.somthing inches) tailshaft th350 alows you to use the original driveshaft used with the 700r4.
th350 dipstick & tube if you don't have one already.
th350 mount.
Kick down cable. Original tv cable hookup location will work fine for kickdown.
Crossmember will need to be moved, on my '83, two of the holes where in the correct spot, just had to drill two more.
th350 speedo bullet. bullet retainer & drive gear to go with the driven gear and whatever gears you got. (700r4 has large diameter driven gear). Just make sure you count the teeth on both when you install it so you know whats there and then use a gps to find out what your actual road speed is at an indicated 60mph and you can select the closest gear(s) to get the speedo right on.
And thats all I remember. Was straight forward easy, and in the end a much funner truck to drive.

Re: 700r4 to a th350?
 

Thank you axle.

Re: 700r4 to a th350?
 

What Axle said . I did have to find a "hybrid"u joint for the rear but the driveshaft was from a 1/2 ton and the chassis was 3/4.