Bw is reportedly stronger than h165. Neither have LSD easily available, topgear has some h165 lsds left. That's why we were talking about phantom grip lockers- poor mans LSD over welding lol.

I didn't think 60 and 63 bell housings were interchangeable. If it were that easy I'm sure other 1200 members would have done it by now. Just see if it says 60 or #63 # 3 on the bell housing. 63 3 is the dogleg L series box.

As for tailshaft if you changing diffs, choose which one and get the right tail shaft for it, and just get a spacer for yours for now. No point chopping a bw shaft to fit a h150 flange.

Are you using auto tail shafts? If you ate then it may be a L series box. If manual input shafts its an a series. Box