Question after converting a 7-1/4 to 8-3/4

roadrunnerh said

I am doing this swap currently. I spoke with doctor diff the other day and he verified that yes, you can use the backing plates from the 7.25 if they are big bolt pattern axles. I have a '75 Scamp with discs up front and drums in the rear (5x4.5 bp). I will be using the whole brake setup from my 7.25 onto my new 8.75 housing.

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Ok, so from what I gather, I cannot use the backing plates from my SBP 7.25" on the 8.75" assembly, right? If that's the case, are the brake parts compatible, or do I need to source new hardware, cylinders, shoes, and drums? What about the driveshaft-is it the same length? Is there anything else you can think of I'd need apart from a center section? My brother said he'd give me his old pig for the cost of shipping-741 with highway gears. I know it's not the big pinion 742 or 489, but it'll only be behind a stock 5.2 Magnum converted to 4bbl with a dual plane intake and 904.