is this an M90?

The internals themselves will be the same between the blowers. A 3rd Gen, is a 3rd Gen. The nose drives however will be different. Upon looking at your comparison pictures, it's possible that this blower was on something else other than a Supercoupe, but it's still a 3rd Gen case.

You can check through the various nose drive selections as well as specs an confirmation on the blower you have here. It should give you a good idea as to what you'll need to be doing. I would consider bolting the blowre to the Saleen lower manifold to mock it up and see how much drive length is actually needed before spending any money on parts. To save some money, you can use the drive snout from an earlier Gen II unit ('89-'93 Supercoupe/Cougar XR-7) as they're the same as the later one and they tend to sell for next to nothing on Ebay, but if memory serves, you're still going to need to exted it further.

I had a brain fart earlier and now remember than the Series I (Speedlab) blower used the M90 and the Series II kits used a IV Gen MP90. Making your 3rd Gen M90 will still be doable, but you're going to have to fiddle with the nose drive lengths....not to mention source, or custom make an inlet for the earlier kit.

Here's a picture of the MP90 on the Saleen Series II kit. Notice how different the inlet and case are compared to the 3rd Gen you have....not to mention its use of an external bypass.





Found this link with a little Google search. There may be some further helpful info there....Saleen Superchargers