I am swapping in a dash and guage cluster from a 91 Z28 into my 85 Iroc and didn't get the vss stuff from it. I went to gm to get a vss module and they told me i would need alot more than just the sensor. they said i'd basically need the whole tail housing. Also, from the diagrams they pulled up, the vss module is in the back. If that is so, what goes in the hole where the speedo cable is now? (i was lead to believe that that is where the new vss goes) also, they said i'd need a metal speedo gear, and that mine's plastic. I've done the 730 SD conversion so, from what i've read, i won't need to do anything with wiring in a buffer. i know the 730 ecm can be changed for the 2000ppm or 4000ppm vss. mine's already been changed for the 2000ppm vss module. Since it has been changed in my prom, why would i even need to get a different vss? can anybody clear this up for me? (especially what goes in the hole that the speedo cable is currentlly in)

 

The VSS sender goes in the tailshaft where the current mechanical drive is. VSS sender is a Hall or pulse generator that sends pulses to the ECM based on vehicle speed. In the mechanical speedo the Hall or VSS pulse generator is in the speedo head unit, then goes to the buffer module. The 91 ECM supports SD and direct input from the VSS sender so if you are running that unit you need the sender and the wiring. Not sure about calibration since I have never done it, that is I don't know if they offer different gears for what axle ratio you have like they do with the mechanical drive. Hpoe this helps some.