The Frigidaire/Harrison A6 has been used in more mobile applications than you can imagine. It's a big, large displacement, nearly indestructible, 40+lb tank of a compressor. However, it has a weak link, The 3 piece ceramic shaft seal was, and still is, always prone to leakage.
The A6 was used on all GM cars and light trucks from 1964 to 1978 or so.
Ford used the A6 compressor on their "High Line" models all through the 70s. Lincoln, Thunderbird, and many full size LTD/Marquis models had the (GM?) Frigidaire A6/POA refrigerant system that was standard on all GM vehicles at the time.