911 Help! I'm doing a TBI to TPI conversion on my 1991 RS 5L. The only thing left to do is the vehicle speed sensor. If anyone out there is driving a 90-92 5L TPI, 4 speed automatic, Z28, I would greatly appreciate the RPO codes from sticker in the glove box or door jam or spare tire well. As the 5L TPI was not offered as an RS, I need the Z28 info. Confused? With this info I can purchase the correct vss and gear for the transmission and keep the TPI ECM happy not to mention the speedo and cruise control. Thanks.