I swapped everything to the 95 model parts its a 90 k2500 LD, but all the ac except the pump 95 r134a parts and originally it was in the condenser now i have it in the evaporatorI just noticed that you have a 1990. Which model is it? Where is the orifice tube in your 1990? If it is condenser mounted, you need the Yellow/White GM condenser mounted tube. Same orifice size as the Red Ford, but intended for a condenser mount.