Would a .2.93 open diff from a 328i fit my 325is?
 

My longtime daily driver (got it when I graduated college 7+ years ago) 95 325is with 216k on the clock sees a good 300 miles+ week commuting. I baby it and manage to get ~400 miles per tank in mixture of in-town and highway driving with 15" wheels, 3.15 open differential, 93 octane and ebay performance chip.

It occurred to me last night that some E36 328s had a 2.93 (or similar, can't quite remember) open diff. Would this work in my car without significant re-configuring? Would it help fuel economy in any meaningful way?

Just a thought. I have my eye on all kinds of wonderful and expensive newer daily drivers like subaru wagons, GTIs, mini coopers etc, but I'm cheap and would love to get to 250k with this car before the interior completely falls apart and the body completely rusts out (both are in progress).