The Stovebolt Site Forums The Shop Area Engine Shop Switch from TH350 to TH700R4?

I have a '69 Chev 1/2T 250c.i. 6 cyl. with a TH350 automatic and the trans is getting very loose, it slips between shifts and leaks out of front and rear seals. I also have a TH700R4 trans, out of a friends wrecked truck, that's from a '87 Chev, but it had a 350 V8 engine. I would like to run this trans behind my old 6 cyl. which has only about 105,000 miles on the engine. Oh, my friend had overhauled the TH700 about 2 months before the concrete truck backed into it. The thing I'm interested in is the trans has an overdrive gear in it. Is this a hard swap? Do I have to get the drive shaft shortened or lengthened? How about the tranny mount position, does it stay put or does it move? Any advice is appreciated. Thanks, Harry

You will probably have to have the driveshaft modified although there is one model of 350 that is the same length. It will be easy to move the crossmember or adapt a mounting plate for the rear mount. The biggest problem will be matching the TV cable to the 6 cyl. carb. It must be right. The results will be well worth it.

Wrenchbender thanks. Does someone sell or make a TV cable kit? Also, from the search I did here on TH700s there is stuff about vacuum switches and running off the brake light switch to engage/disengage the lockup torque converter? Has anyone a schematic or whatever you call it for this kind of set-up? Thanks, Harry

The subject of a cable for a 6 has been brought up lately. Try Bowtie Overdrives. There are several kits available for the lockup or you can run without it. I,ve got a system I use useing salvage parts if you are interested.

Well, finally Hughes.net Satellite dish internet service is back working, out for a coupla days.

Wrenchbender, I am very interested in your system using salvage parts, please clue me in, please. Did you make your own bracket, or whatever, for the TV cable, I think they call it? Everyone says that the cable thing is real durned important or the thing won't shift right. I can MIG weld, sorta, not the greatest but gets by, usually too much heat. Thank you, Harry

I was refering to the lock-up system. I get a vacuum switch from a late 80,s van, it has a green & a blue wire on the connector. Get a 2 prong oil pressure switch for or from a mid 70,s chev for an electric choke. Mount the vacuum switch on the firewall. Put the oil switch in the 4th gear plug, it is the lowest plug on the right hand side. Run a wire from the acessory circuit through a fuse to the vacuum switch. Run the other wire to the oil switch & run the other from the oil switch to the connector on the trans. Ground the other wire from the connector.There is another wire on the trans connector that you don,t use . I will have to look tomorrow & see which one it is. Run a vacuum hose from ported vacuum on the carb to the vacuum switch. I,ve never put one on a 6 cyl. You will have to get a long cable & fabricate a bracket. One of the websights shows the arc that the cable goes in on the throttle lever. It can be no more then 1 1/8" from the shaft. Sounds complicated but after you have done it once it,s understandable.