E36 Help

I recently was offered an opportunity to purchase a car that I had looked at for awhile, a 94 BMW 325IS. 

Mostly well sorted, needs some cosmetic work and some maintenance to be caught up on as its been sitting for the last 2 years since he recently purchased a crossover to tow behind his RV. It has had some extensive work done to it previously to make it reliable for him so it would be easier to look after on the road including:

A GM Performance small block, a camaro 5 speed transmission, a custom one piece driveshaft, 2 sets of wheels/tires (winters and summers), recent KYB shocks/struts and MSD Fuel Injection. The A/C doesn't work at this time but it just needs a line made up since everything is there but the BMW line didn't match the GM compressor or didn't reach, I can't remember exactly right now. And the OEM tach doesn't work but it has a small tach installed on the dash so I can keep an eye on the revs. 

The rear differential is the stock unit. I have read about the rear subframe mount weld in plates and that is definitely on the 'To Do' list, but I am uncertain of the life expectancy of the rear differential at the current power level (Crate engine was rated 340hp, but has exhaust work and fuel injection vs the recommended carb). I don't plan on any further power increases for the car except the negligible increase when I can afford the BORLA cat back exhaust and getting the fuel injection properly tuned. 

My question is there a decent rear differential to look for? Or will the OEM one be fine for this power level for an extended life? Plans are to daily drive the car and possibly the occasional track day when budget allows. Will the OEM differential survive? Or is there a decent differential I should keep an eye out for? Also is there anything I should be prepared to look after to keep it going for a long time?

Thanks in advance!

The turbo e36 m3 guys are pushing 1000hp on the stock rear end. I have no idea what this car would have, but the m3 rear end is a bolt in. 

I would go full send on this, wait till the rear end pops(if it ever does) and swap in a m3 unit. 

I dont think the M3 is any stronger, just has an LSD. 

If you want a beefier one, the european e36 M3 is a big case and much beefier. 

Black out the grilles and call it good.

Can't tell you much about the diff (except that most BMW diffs seem pretty stout), but I can sell you set of Dinan lowering springs for cheap - they're just taking up space in my garage.

Perfect, I'll definitely be getting it the subframe reinforcement plates for the rear, then not be too worried about the rear end grenading. I'll be sure to check the fluid level and enjoy the car. 

In Reply to 02Pilot 

I will definitely keep them in mind!

Hi, nice car.  I used exactly that chassis for my V8 swap.

There is a motor swap forum on Bimmerforums.  The E36 medium case diff seems to hold up well.  There are turbo guys with monster horsepower, and drag racers with sticky tires, that seem to damage 'em.  I expect you'll be fine.

Beyond the rear subframe mount reinforcements, keep an eye on the rear trailing arm brackets for cracks around the bolt holes, and the front subframe ears where the motor mounts bolt up.  There are reinforcement plates available for both those spots.