Ok ive decided to start swaping my 98 pcm to go to the 99 pcm and so far ive got 4 wires that the 99 have no spot for! Does anyone know where these wires are supposed to go??? On the 98 its labeled pin 24 Blk/wht-sensor ground jumper. Pin 55 DK GRN/WHT- VSS OUTPUT SIGNAL. Pin 69 BRN-EVAP PURGE VACUUM SWITCH SIGNAL. Pin 75 GRY-LEFT AND RIGHT FUEL TANK LEVEL SENSOR GROUND. These are the explanations that my 1998 manual gives me for these wires but i have a wiring diagram i bought for a 1999 corvette offline and i can't find a spot for them, please help me or call my if you wish. 336-225-7932. Thanks Adam Calley.