The 8 1/4 thread

are you sure he has an offset housing or its just not a case of the pinion is smaller because of the wrong gear ratio on the wrong carrier ( carrier break issues) 2.45 and numerically lower uses one carrier because the pinion gear is so big the ring has to be moved further out. 2.56 and up uses another carrier because the pinion is smaller.

some folks make a spacer to put on there but im not sure how good running a spacer is like that long term but might be an option to use what he already has and solve the new bolt issue at the same time. So maybe search spacers for it and maybe even come in a kit with bolts seeing they will need to be longer to get through the spacer.