Here we see the two diff' covers
side by side. The M Coupe cover has much more extensive fins, mostly down below the
differential, where the fins protrude into the air flowing below the car.
Note the 10mm hex size on the old E30 drain/fill plug vs. the 14mm hex size on the new
M Coupe drain/fill plug. Be sure to have the correct size on hand if you decide to
go with the newer style plugs. I got nice stubby 14mm and 17mm (for the tranny)
hex head sockets from Steve D' at the "Ultimate Garage".
The red arrows point out the vent outlets for the two types of differential covers.
The E30 has a little vertical tube, which would actually make it very easy to attach a
hose and run it up to an overflow/catch tank in the trunk. The M Coupe cover has only
a small pin-hole. However, the M Coupe cover has a nice baffle on the inside (shown
on a different page) which the E30 cover does not have.