Thanks, Stewart
Finally something definitive. There's nothing at all in the 48-51 shop manual. That should pertain to 47-55 3100's.
Interesting, I just looked at a 55 2nd series shop manual and it specifies 45-65 ft lb for 1/2 tons. That's on page 10-12. It specifies 65-90 ft lb for 3/4 ton and 1 ton, and 250--275 ft lb for 1-1/2 ton and 2 ton.