[rcrta]

Anyone changed out a th400 to and overdrive trans.If so which trans did you use?Any mod have to be made(driveshaft crossmember cooler lines shifter speedo)?Thanks

[SteveGB21]

On changing to an overdrive, only the 200-4R will fit without an adapter plate due to the bellhousing being universal. The 700R4/4L60(E), and the 4L80E all will need an adapter plate, since it is a Chevy only bellhousing. Any of the transmissions that have an E at the end (like the 4L60E & 4L80E and their upgraded cousins as the 4L65E/4L70E & 6L80E) will need a computer and a special connection from the computer to the carb for it to work.

I have heard when changing from a TH-400 to a 200-4R, you can use the same crossmember. Seen on the '68-'72 models that getting the GTO emergency brake cables with the TH-400 is a must. The driveshaft would need to be shortened. Also, the slipyoke from the Powerglide/TH-350/TH-200 can be used. One of the hardest parts that you would need to locate is the dust cover off an Oldsmobile 307.

Not too sure about the speedometer.

[Goatracer1]

I installed a 200-4R in my 1967 GTO. Was done in a weekend. I followed the article that was in HPP Magazine and it was easy. Same crossmember, shifter. Mileage went from 6 mpg on highway to 15mpg on supercharged 434 cid engine with 3.89 rear gears. If you decide to do swap get back issues of HPP and just follow.