Yes, I'm saying the output shaft on the BA10 is 21 spline and all other 6 cyls with 231's are 23 spline. The AX15 is a good replacement for the BA10 but the bell housings are different. The tranny has to stay with it's own bell housing. The transfer cases should be the same length but the transmissions are not. The input shafts in the two transfercases are interchangeable. The BA10 is easy to identify because the case is split lengthwise. If it's a 5 spd with a fore and aft section separated by an intermediate plate 1/2" or so thick, it's an AX-15.