Non-Dealer Installed AC Question

When I bought my 1991 Escort LX new, the dealer had a local company install the AC system. A couple of years ago, I needed a new manifold for the AC, but had to have it custom-made because the compressor connection was reversed. If I ever need the compressor replaced, how would I go about finding which model to get. I guess I'd probably need to have the old compressor pulled and check model numbers?

Thanks in advance!

Frunobulax