GM sent out a Dealer Tech Bulletin in 68 or 69 that clarified this. The reprints of GM Firebird maintenance manuals (even ones you buy brand new today) may still show the original (incorrect) procedure. I think Geoff has the bulletin somewhere on this website.
However, since you do back off a bit before lining up the pin, there sometimes IS a wee bit of play, barely felt when grabbing the tire.
'68 428 HO M3 Monster, 4-on-the-floor! Need I say more?