The car I'm working with has a bad VSS (no speedo activity and throwing code). It is a 91' RS body and 700r4, but it's mated to an 87' TPI ECU. So which year does it need? Also it seems there are a couple of sizes available from autozone, depending on the year.

 

You need a VSS to suit the computer not the car
VSS pulse signal changed in '90 from 2000 to 4000

 

That makes sense. But will an 87 Vss fit a 91 700r4? I ask because the parts look different. Or are all the 700r4's pretty much the same?

 

The connector plug may be different but the fitment in trans is the same

 

Ok, the only thing that looks different is a bracket on the 91 vss.

This is the pre 90 Vss



And this is the 90+ Vss

 

Old VSS' had a hold down bracket similar to the one on the distributor

Older VSS' reversed the wires. Before you buy a new VSS, switch the wires and see if your speedo works again

 

The VSS went out before the swap, so it's dead. I went ahead and ordered the sensor that is correct for the transmission and a Dakota SGI-5 to correct for the older computer and the 3.73's. Thanks for the wiring info, that may come in handy depending on how it was wired back to the ECU.

 

ANyone know the part number for the gear-drive speedometer AND the VSS pulse (2000)?

 

Discontinued from GM (was the B4C VSS)

Look here
http://www.jagsthatrun.com/SpeedSensors_Order.html

Or here
http://www.transmissioncenter.net/sp...n_______va.htm

 

Thanks, Pocket! How about the one that fits inside the 700R4 trans speedometer mount are - AND has the gear-driven cable(with 2000ppm)????