I am trying to help a friend without a computer-

He has a 72-73 Duster which had 9" drums, slant 6 and a 7-1/4" rear (I am told). He wants to switch to the larger bolt pattern and disc brakes. He has already bought a 8-3/4" rear, and the SSBC disc kit. However, the kit requires 10" spindles.

Do the 10" spindles have to come from an A body, or are there any other things that will work? Like later B, M or F spindles?

Thanks-