Ford 8 inch Rear End, No TR - Stupid Question

Hi everyone!
I'm trying to figure out the ratio of a rear end.  I may be going loopy but
when I spin the pinion flange it seems as though the brake drums can spin
independently and my chalk marks don't seem to be a reliable means of counting
the number of revolutions per turn(s) of the pinion flange.

Am I missing something?

Thanks!

Wayne

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