R154 and AX15 are from the same family of transmissions and they both have the same bolt pattern for the bellhousing. Big difference between the two is gear ratios, the R154 is geared for a sports car (MK3 Supra Turbo) while the AX15 is for a truck. Pretty sure the input shaft is different between the two, and not sure about the shifter location.
I know that someone on here has done an AX15 swap with a V8, might give you some useful info.
I used a 4 speed bellhousing.
