I have a 1986 firebird that came with a 85 mph speedometer. Its electrically driven. I want to put the 140 gauge assembly out of a 1987 trans am GTA in the car. it was also electrically driven. they were both auto cars, however i just did a t-5 swap in my 86. The question is- will the 140 speedo even work? do i need a different buffer box? what VSS should i install in the tranny? i have a couple but one is from a 85 camaro t-5 and the other a 94 firebird t-5. I know one is 2000 pulse and one 4000 pulse but i really dont understand all that jazz... so if someone could tell me what all i need that would be awesome.. thanks!

 

I have an 87 GTA and it has a yellow and purple wire from the VSS on the trans to the yellow buffer box under the dash passenger side.

I don't remember the color wire that connects to #15 on connector 2 that the instrument cluster connects too, but it's for the input of the speedometer from the yellow buffer box. On connector 1 the "G" plug is for the ground side of the speedometer from the buffer box also.

Not sure about the pulse thing. I had to rewire speedometer due to previous owner hacked the harness.

Hope this helps.