Hey, Great car, I love those 544's. However I'm much better suited to answer questions about newer Volvo's. My suggestion is to check out some of the Volvo specific forums. My guess is you'll be OK, but it's a guess. Good Luck!
Bret, I found out that GL-5 contains an ingredient that is harmful to the brass and bronze parts in the tranny mainly syncronizers and bushings. GL-4 is the correct lube to use in the gearbox, I'm going to use REDLINE MTL, it happens to be a synthetic. The GL-5 is apparently OK for the differential. Thanks for the response. Zoneman