I have a 1990 GMC 1500, 305 motor. Runs great currently. I can not figure out how the smog control works on this motor. I have a service manual, the big thick one, and can not find any info there. it has a diagram of the motor complete, but the picture shows no smog pump. I looked online, classic industries, and they don't sell anything for it. It has [I believe] an EGR valve and an evaporator and the coffee can behind the headlight. Does anyone know how the emission system works in this model? Thanks.