Hi Eric,

Here is a page from the master parts catalog. http://chevy.oldcarmanualproject.com/1929_57chevyparts/57cmpc0569.htm It looks like the front brackets are the same 1/2 and 3/4 ton but different front left and right. Same part numbers for middle bracket left and right. But for the rear, it looks like a different part number for 1/2 and 3/4 ton.