when i used to talk to Jeff at Eaton, he verified the 98-04 rear axle had 28 splines. he didn't say anything about a gap between any of them, so i doubt that's the case. we have also heard from solomiata that the rear diff is a 7.5" ring gear, not an 8" ring gear and as can be seen from looking at the housing, it is not as large as a toyota 8" housing so it is safe to say, the ring gear is prolly not as large as the the toyota 8" ring gear, but it is visibly larger than the verified 7" front Kia ring gear, so it is safe to say that the Kia rear ring gear is larger than 7" and smaller than 8". ron, if there is an rx-7 or miata diff that measures 7.5" that may be the one that will work. this is the only reaon i mentioned to look into ford stuff, because the broncoII and ranger rear axle is a 7.8, which is very close to 7.5 and therefore, may be close enough, with light machining to be interchangable. also, from what i have seen, normally, the spline area is actually a larger diameter or the same diameter as the majority of the shaft, not normally larger.