A few of you had emailed and asked me to let you know how my tranny swap project went.
I have an '81 which had the TH350 3 speed automatic. The gas mileage and highway speed RPMs were killing me so I found a TH2004R for a swap. The 2004R was made for Cadillac/Olds/Buicks in the 80's and is a good easy swap. First and second gears are lower than the TH350 making those 190 factory horses seem just a little more peppy. Third is geared the same as the top gear on the 350, and the overdrive is just frosting on the cake. Many people swap a TH700-R4 because they're easier to find, but then there are other compatability problems. The 2004R is the same length as the TH350, eliminating the need for shortening the driveshaft (unlike the 700R4), and the rear yoke is also the same size (27 spline). The bell housing bolts right up.
There were only a few modifications. The transmission oil lines were slightly different in location but were able to reach with about 2 minutes of VERY minor rebending. The torque converter out of a 350 is different than the 2004R, it looks like it'll fit but, believe me, it won't. I bought a crossmember for $180 from BowtieOverdrives.com, but someone with moderate fabrication skills could make or modify your old one easily. I also bought a new shift detent plate but, after comparing the new to the old, realized that a monkey could have modified the old one to fit (or even just use the old one as is without the proper shift stops). Lastly, you may need a throttle valve cable kit, but your current kickdown cable can be used for that and adjusted to your shifting tastes.
Took a drive around the block and everything seems to work great. Overdrive is wonderful and I'm told I should get about a 20-30% increase in mileage. Took me about 8 hours to do by myself. Feel free to e-mail me if there is something I missed or you have questions.
I have an '81 which had the TH350 3 speed automatic. The gas mileage and highway speed RPMs were killing me so I found a TH2004R for a swap. The 2004R was made for Cadillac/Olds/Buicks in the 80's and is a good easy swap. First and second gears are lower than the TH350 making those 190 factory horses seem just a little more peppy. Third is geared the same as the top gear on the 350, and the overdrive is just frosting on the cake. Many people swap a TH700-R4 because they're easier to find, but then there are other compatability problems. The 2004R is the same length as the TH350, eliminating the need for shortening the driveshaft (unlike the 700R4), and the rear yoke is also the same size (27 spline). The bell housing bolts right up.
There were only a few modifications. The transmission oil lines were slightly different in location but were able to reach with about 2 minutes of VERY minor rebending. The torque converter out of a 350 is different than the 2004R, it looks like it'll fit but, believe me, it won't. I bought a crossmember for $180 from BowtieOverdrives.com, but someone with moderate fabrication skills could make or modify your old one easily. I also bought a new shift detent plate but, after comparing the new to the old, realized that a monkey could have modified the old one to fit (or even just use the old one as is without the proper shift stops). Lastly, you may need a throttle valve cable kit, but your current kickdown cable can be used for that and adjusted to your shifting tastes.
Took a drive around the block and everything seems to work great. Overdrive is wonderful and I'm told I should get about a 20-30% increase in mileage. Took me about 8 hours to do by myself. Feel free to e-mail me if there is something I missed or you have questions.