Sorry, i didnt catch that the axles you have are the bbp. I have no way of knowing, but maybe your housing was a wider piece narrowed to use the original a-body 8 3/4 axles. They would give you the 5x4 that you want. Of course you realize there is a much wider selection of wheels for the 4 1/2 pattern.
I would suggest you talk to Dr Diff about your problem. Have all your dimensions of what you have, on hand so you can answer his questions. His reputation for help for mopar guys on this forum and b-bodies is absolutely solid gold.
