Okay, so if the bearing retainer is 4.80 it is strictly for a big block? And if it is 4.30 it a small block?The reason I'm asking is I have a 74' 360 4 speed Cuda.I never had the original trans for it, and the bellhousing that came with the car (in boxes)is for a 72'-73' 318 -340 #3515734 .It has the small retainer size in it.I dragged home a 4 speed it has the 4.80 opening.Is the 74' bellhousing #3743959 a unique piece? If so what is different about it? It looks like I have trans and bellhousing that I cant use,am I correct?Thanks for any help or suggestions!