Converting '87 MAF to 90 SD. I've got a '90 SD harness, but the trans only has a 2k VSS. I've read here that by changing the prom and repinning the harness I can run a 2k ppm on a 730 ECM ? The car wont have cruise and the dash will probably be a custom unit from dakota digital that I guess I can run on the 2k output from the ECM ? If the above is not possible can I just by the 4k VSS and bolt it in to the trans or do they use different wheels inside the tailshaft ? To put it another way, will the magnetic type VSS "read" the gear wheel inside an '87 trans ?

if the '87 trans has a reluctor on the shaft, then yes it will. my '87 trans has a gear drive on the shaft and the vss is on the back of the speedometer housing. you can pull the tail housing off the trans and replace the gear with a reluctor and the proper vss for the speed density set-up and go with that. but no, the magnetic type vss will not read off the gear wheel inside the '87 trans. it has to have a reludtor/pick-up to read off of.