Well about a month ago my transmission in my '85 T/A (305) started going in and out of overdrive when I was on the freeway. I was crusing around 70mph at 2K, and then it popped up to 2400rpms or so, then go back down after I played with the throttle. I called a transmission shop about this and they said it sounded like the 3-4 clutch was going out and it would cost around $600-700 to fix, minus any other parts (if the transmission was getting worn out somewhere else...I'm not sure how many miles are on it, but there are 135K on the car.) I will be dropping in an LS1 with a T56 one day, and I was thinking of driving the car until the tranny finally gave out and just put my $700 towards the swap. But it's annoying, so I thought that if I could fix it for cheaper than the shop, maybe I'd try that. Has anybody tried replacing the 3-4 clutch on this tranny, and is it too much work?

It may be a bad TPS and it is causing the TCC is unlock.

RBob.

That's what I was thinking at first. Is there a way to adjust the tps?

It may be adjustable on an '85 TPI. However, if it is bad (maybe just worn out) it needs to be replaced. A TPS is an electromechanical device so there is a wear factor.

RBob.