Could someone tell me where to find the model number on my tranny? It is a 1990 1500 with a 5 spd manual, and I can't find the number stamped anywhere. I am trying to change the lube, and have been told 500 different things, from using only syncromesh to using ATF to 80W-90. I am 99.9% sure I need syncro in there, (as per the Chevy dealer) but I know it is only for specific models, and that you can really screw up your tranny if it isn't supposed to be in there. I am just trying to double check by matching the part numbers, but I can't find the tranny number. Any help is appreciated.