nytrdr24
+1y
your right, the 12a shouldn't have individual coil packs.....& I don't think that there is an issue with the trucks tranny and the 12a tranny....just measure to check the input shafts length, if there is a difference, then I might trim the 1/2", you might consider just using the rx's tranny if the tail section has the shifter tower in the same location (can't remember)....
1st-4th gears are the same in the trannys, 5th is geared a little taller which would give you better gas mileage on the highway.