If swapping engines...

[bolognablake]

If I'm swapping a S50 or M50 into an e30, is their any advantage or disadvantage with going with a 318i/is or 325i/is?

Just wondering.

[GarrettM]

M10 318i is the lightest E30.

[TwoJ's]

There are wiring differences as well (I think). Aside from that, you just need to look at the options that came with each car. The 318is had a 4.10 small case. You wouldn't want that for an s50. But in reality, just find a car that fits your needs and wants body wise, regardless of model.

[Mossman]

best body, worst motor/tranny. If you want an airbag you need 90+, and the early 318's were old style body/bumpers but light with a small case diff, late 318's with the 16v look just like 89+ 325's but also have small cases, but that's easily remedied and 3.73 might be too much gear either way.