I've got a 90 rs with a 305 tbi that I just put a new 700r4 in. Well, ever since I put it in and hooked everything up, when it would shift from 1st to 2nd, the engine would die and the speedo would read 115 mph. Well, to make a long story short, i tired unplugging things on the tranny and found that when i unplug the electrical connector on the speed sensor the car would shift fine and drive normal. So, naturally I changed the sensor, but the new one has the same problem as the old one. Everything seemed to work fine before I bought the new tranny, and I've run out of ideas. Umm... i don't know if this has anything to do with it though, but the old tranny had a sensor with drive and driven gears and the new sensor uses a magnetic pickup for a metal gear on the output shaft.
Thanks for your help...

- Dave

 

Try and get the numbers off the VSS Buffer box and see if that box is different for the magnetic pickup speedo. The box is a yellow buffer box under the dash on the passenger side. If it is different then you can get 1 from a salvage yard from most GM cars. Like I got 1 from a caddy that was a 1989 and had the correct box for me. Sounds like that buffer is not compatible...