I know how to identify which pump is the bigger one by the crankshaft and all and using the tag for a reference. Here is the question. Were the larger stroke compressors used in larger vehicles? The reason I ask is the compressor I have located at the local junkyard is of course still in the vehicle and they won't let me yank the pulley to properly identify the crank shape. I really don't want to shell out the cash for the smaller compressor. The vehicle is a 1978 Ford Fairmont. Not sure of engine size in this particular POS. Anybody have any clues?