: TH425 question

04-08-13, 06:01 PM
Hello all.....I ran across your web site while doing research on the GM TH 425 transmission. I hope this is the correct place to ask this question.

I am in the process of building a Countach replica and intend on using the 425. Since the car will weigh not more than 2200 lbs, I was looking for a way of changing the final drive ration to reduce engine rpm on the freeway.

I ran across reference to "Caspro power drive" modification which changes the ratio in the chain section of the trans which is exactly what I am looking for. I have been unable to find anyone that sells this conversion for the transmission. Is this thing still available and if so from whom? A link would be much appreciated.

I fell in love the TH 425 when I purchased a motor home a few years back and the original owner had purchased a factory new transmission for it, just in case. I sold the motorhome but kept the transmission, looking at how beefy this thing was and the fact that it was an automatic made it perfect for my needs. I'll leave the shifting to the kids, I just want to enjoy the drive.

Also is there anyone else out there that is using the transmission in a similar way, I would love to exchange photos of my setup and see what others are doing as well.