The 4.10 gears were what the 68-72 trucks had; IIRC the 4.10's in my '63 dually had 1972 stamped on them. The 4.11's were just an earlier version with a different gear tooth count; 9 pinion teeth and 37 ring gear teeth, where the later 4.10's were 10/41. I just thought I'd note that there were actually both 4.10's and 4.11's made for the Eaton rears.
AFAIK, the 4.11's were just a 63-67 3/4 ton thing. The GM docs from the Heritage Center site show them as an option through those years, with earlier stuff having no mention of them, and later stuff all being 4.10. In '68 they also show 4.57 becoming the standard ratio for one ton trucks, with the 4.10's being an option. (Prior years had 5.14 as standard, with 4.57 the only option.)
BTW, it's a neat site if anyone here hasn't seen it before:
http://www.gmheritagecenter.com/gm-heritage-archive/vehicle-information-kits.html
