There are at least two different compressors in the GC8s. The pre 97 looks the same but has a smaller ID on the ports and are not interchangeable. Easiest way to tell if it is an early or late system is to check the condensor. Silver/unpainted is early, black is late. 97 being a changeover year tend to have a mixture of one or the other.
You may already know this, just thought I'd post it up here in case you don't so I can save someone from having a future headache.