Mainly spinning 1 tire...

iThe 8 3/4 is a "quick change" setup. Kind of like a Ford 9 inch. You can tell cause there are no cover bolts on the rear "Pumpkin. You basically pull the drums, remove some bolts for the axles, slide them clear of the differential, remove the u joint straps, remove the differential bolts , pull the chunk, then slap another one in. It worked really good for the guy who drove a street gear, then swapped it out to go to the track. For ease, I would recommend you obtain a Sure Grip, a gasket, and put it in. But keep in mind if it is a used unit, someone may have played around with it. You can set up pinion depth and backlash on the bench before you install it.