I double-checked and just want to add something. See, the 318i was fitted with the Getrag S5D 200 G transmission up to 9/1992, but then they started using the Getrag S5D 250 G. The 325i always used the Getrag S5D 250 G.
If you have the 250, you're good to go. I don't know what the spec differences are between the 200 vs the 250, but I think they should bolt right on to the engine. I'd try to make sure that if you have the 200 (most likely, since I see your car is a 1992 model year), that it can handle the torque from the M50 engine.
You should be fine, but I can't make you any guarantees. Run a few online searches. You're bound to find tons of useful info.