Bought a 87 Firebird, previous owner did a 2.8 v6 to carbed v8 & 700r4 swap, the tranny has the 2 wire speed sensor, 1 yellow and 1 purple wire, which are butt connected to the harness wires of the same color, traced the wires up to passenger compartement, they go into a yellow buffer box, then a green goes to the guage. When i'm moving the speedo is pegged at max, when stopped it goes to 0, any help would be MOST appreciated.
-BBBoonze
Boonzey@gmail.com

 

Sounds like it has a truck 40-tooth trigger wheel instead of the proper 4-pole VSS. In this case look for a DRAC from a truck and wire that in place of the 4-out buffer box.

This is actually a better way to go then getting the correct VSS. As a DRAC box is strap-able for different rear ratios and tire diameters.

RBob.