the front brg retainer is the issue , it came in 3 sizes , 4.35 using the 307 brg , 4.80 & 5.12 " diameters both using the larger 308 brg , the 5.12" retainer can be easily machined down to 4.80 to fit the 4.80 belhousing but you are sunk if you have a 4,35 hole in the belhousing with either of the larger retainers diameters . If you have the 4.35 retainer on your trans there are adapter rings so you can use the 4.80 belhousing