has anyone heard about a shaft modification to the m90 that would allow the charger and lower intake to bolt right up to the mustang 3.8 in 94-98 models and use the factory serpentine belt and if so have any details on or about it?
Never heard of anyone doing it in this scenario. I know eaton sells custom shafts and I have seriously considered this with a m112 for my 5.0. I've seen a few web pages with the M112 to 5.0 swap in progress but haven't seen any completed using that method.
Yeah, it's easier in the 94-98 motors, but what most people will tell you, is that you should just purchase the whole motor. The M90 isn't exactly a direct bolt-on. For the 99-04 guys, there are now M112 kits available for a very reasonable price.
Also, I wouldn't extend it more than 2" like I did. And I wouldn't even do that without some kind of support. It's very hard on the snout bearings. I am using a Vortech race strut with a custom made crank pulley. The other end of the brace attaches to the front of the supercharger shaft. Giving support on BOTH sides of the pulley. It prolongs snout bearing life and also front main bearing life.