I would have thougt for sure someone would know the answer to this one. I pulled the pugoet down the other day I just did not have the ax15 at the shop to check the bellhousing bolt patty. I think they are the same according to reading I have done on novaks website. Anyway I will pull the trans back out and get an answer to this question for you guys.
i bumped this thread a few days ago, and i don't think i thought hard enough about the question. i believe that the 4.0 and 4.2 bell housings are the same. mu husband is (slowly) building his YJ up. he took out his AX-15 and swapped in an NV3550 out of a TJ. the NV3550 bolted right up w/o any modifications. the only difference is the AX-15 has an internal slave cylinder and the NV3550 has and external slave.