Robert,
I just obtained a SM326 Saganaw 3 speed with the R10Q BW OD. I removed the side cover to look at the reverse
lock out rod you were concerned about. It is solid and working normal.
I don't see any way it would work in the condition you described.
Fred

1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine