I was wondering if somebody out there could give me a little insight. I want to swap from 700r to a th350. I need to know what has to be done as far as the torque arm, any linkage mods, driveshaft mods. 83 Camaro with a mild 350.

 

Depending on what th350 you get, you may or may not need a longer driveshaft. There was a th350 with a short tailshaft and a th350 with a long tailshaft. The long tailshaft is the one you want if you want to keep your stock driveshaft. I got the shorter one in my 87 and had to get a longer driveshaft cut. You'll need a TV cable, you can pick that up from a local autoparts store. You'll also need the TH350 adapter kit that B&M makes. It has an adapter that moves the rear transmission mount up a little bit, and a bracket that allows you to hook the torque arm up..I got mine from summit, part #BMM-30299. It'll be about 90 bucks with shipping. All you'll need to do is move that rubber pad for the torque arm off the tail of the 700r4 and put it on the adapter plate. They give you some pretty good instructions too. The speedo cable might hook up. I actually put the end of my 700r4 onto the end of the th350 I had. The speedo gears and work on the th350, and the tail from the 700r4 will bolt on nicely. Get your tv cable and the adapter plate for the torque arm and trans mount and you're good to go.

And I also should mention this. Although you can move the tail of the 700 to the 350, the 350 is actually shorter than the 700, and that's why you need the adapter plate for the torque arm. If you have a long tailshaft th350, you wouldn't need a new driveshaft, but you'd need the torque arm and tranny mount adapter regardless.

 

I'm still wondering why you guys want to replace a 700 with a 350??? The 350 isn't any stronger than a PROPERLY built 700, and you're losing 4th gear. This swap only made sense 20 years ago...when there weren't any good parts available for the 700. We've got 700's surviving very successfully in mid 10 second cars.
To answer your original question...The CORRECT way to do the swap is with a Fitz-All kit. This kit comes with the proper output shaft, and a spacer block which allows you to reuse your original 700 tailhousing. This make it unneccessary to alter your torque arm. The spacer block is also drilled in the proper location to bolt the mount in the original location, as it is on the 700. You need the 700/350 swap specific tail shaft because it allows you to move the drive speedo gear to the proper location on the shaft to line up with the hole in your 700 tail housing. These kits are getting harder to find, and my supplier no longer stocks them...Simply because nobody does 700/350 swaps anymore.
You'll also need a 350 specific dipstick and tube, along with the proper kickdown cable for your application. If my memory from 15 years ago serves me correctly, I believe the Fitz-All kit comes with the dipstick and tube.

Frank

 

I put the th350 in my car because it cost me 200 bucks and I was swapping from v6 to v8. I had already put 3.5k into the engine and I was running out of money for a new transmission. A high performance th350 is also a little cheaper than a 700r4. I got a quote from a transmission builder here in town, 700 for a hi-perf. th350, 1200 for a hi-perf 700r4. Granted the 700r4 is a great transmission, I never had a problem with mine, but free/cheap is hard to pass up . All the guys at the drag strip use th350's, I figured that was a good way to go.

And besides, your method is not any more "correct" than the way I did it. There's several people who have done it this way, it just requires more work that the fitz-all kit, if that's still around. And while it doesn't make sense to do the swap nowadays, he has a 20 year old car, and it could be the same transmission. While we are in a new era of toughly built car parts, our transmission were built in the 80s, where the swap made sense,and still does make sense with a 20 year old trans.

 

Thanks for all the info, I really appreciate it. The reason I am doing the swap is that I picked up the TH350 for swapping a windshield out of a 80's suburban into an 80' pickup, it took all of about 10 minutes to get the job done. The guy when I talked to him origanally he told me the tranny was an 700r4, after I was done with the windshield, we loaded the tranny in my van and I realized it was a 350. The tranny is clean, not all caked with crap, and the fluid looks great.