Go back and reread the second paragraph of post 7.
What he's telling you is that you may or may not get an actual quick ratio box.
I can vouch for this, guy at work bought one for his "84" MCSS,* it was a regular 800 series box.
Most of these mainline rebuilders take all the cores apart, separate the pieces into separate piles, and reassemble with whichever part happens to be at the top of the pile.
FWIW, my 83 Malibu wagon had the 12.7 800 series box in it from the assembly line
*While titled as an '84 with a VIN plate to match, it was born white with red interior, had the big mirrors, 86/87 gauges, 3.73 axle, and a very obvious spot where the SPID label had been peeled from the decklid. I said "tag job", but he didn't care. I didn't crawl under the dash to check the VIN rivets, but I'd bet they were wrong