Tranny swap in my 73 C20. Going from a TH350 to 700R4. Need help.

[bigbird90650]

Hi all. I'm going to do a tranny swap in my 73 C20 2wd longbed. I know that I'll need to have my driveshaft shortened. My truck has a 2 piece driveshaft. I will be shortening the short one but will the shortened one work cause it will have a new angle going into the center support bearing? I have a stock "on the column" shifter. Will it shift through all the gears on the tranny? Cause obviously there will be another gear on the tranny to shift into. The crossmember looks like it's gonna work ok, I just have to slide it back a little and drill some new holes on the frame for it. Any other issues or helps you guys can give will be great. I've never done this before. Thanks so much for your help.

[winky]

I did the same swap with my 4x4, you will need to move the cross member. The 700r is I belive 2-4 inches longer (same as th 400 I believe) you will also have a shift cable that you will need to hook up to your throttle. It will require a bracket, I personally prefer one from a junk yard the after market ones give me trouble. As far as the shifting goes mine shifts fine besides not being able to put it in low. I may be wrong on some things but I put a 700r4 in mine and these are the things I can remember running into. Hopefully someone else can give more details?

[bigbird90650]

Thanks Winky. I hear that the adjustment of the TV (shift) cable is critical and if I screw it up I can hurt the tranny pretty bad. I'm a little nervous about it. Thanks again for your help.

[winky]

^^^^ same here ive been told it can cause you trans to burn up over time... im not a tranny expert so hopefully someone here that knows a little more can help

[79GMCChris]

BigBird-

Take a look at Phoenix Transmission's Website, they have an article about setting up and adjusting the TV cable on the 700R4.

Here's a link:  http://phoenixtrans.com/FAQ.html

Good Luck,
Chris

[bigbird90650]

I measured my TH350 and it has the 9" tailshaft on it. YIPEEEEE. It is the same length as a 700R4. No driveshaft shortening. YESSS. I picked up a good used 700R4 for $200 with converter and cooler lines out of a 91 Suburban. I also bought the tilt steering column and shifter linkage for $40 so it will shift into ALL of the gears and the indicator will show that it is a 4 speed overdrive now. Thanks for all of your help dudes.

[Jason S]

Sounds like you got a good deal. 

Take photos of the swap so that we can all revel in the fun.