The shop manual describes the "Drive Line Rear Axle (Corporation) 2 Speed". "Corporation" must be the "driveline type", Whereas; Timkin/ Rockwell obviously the manufacturer(s). Also; "vacuum" (not "air") is correct.
Please correct me if I got any of that wrong.
From looking closely at the axle plate's broken ear & U-bolts, it appears that 40 years of rust/ rot took it's toll (& probably loosening too). I learned that these plates' design are great for collecting dirt & water in top at the U-bolt areas. Definitely worth a periodic check & clean.
Thanx.
CFFC
Don