i haven't got ahold of anyone at mazdacomp yet, seems that they are on vacation.
i'm pretty sure you can fit the comp dif in the 99 housing, just have to have the older stub axles to lock into the diff. i'll look at some stub axles i have and see if maybe the m2 axles might be the same. i know the normal LSD stub axles are different lengths, and don't lock in right.