Rear disc brakes

I was at the junkyard yesteday and a 93 Mercury Marquis caught my eye. It has a disc brake rear end. Any body know if this set up will fit an 8 1/4 or 8 3/4? I couldn't get the disc to come off so I couldn't measure from axle flange to housing flange. I will go back this week with a few extra tools and get that sucker apart to measure. Is the A body 8 3/4 and 8 1/4 axle flange to backing plate measurements the same? If no one answers this I will update ya'll. :salut: