Well, I don't know where it came from but a fellow bolter in Mi. sent me a pumpkin that is 3.90.... .he says it came out of a 56 or 57 pickup. I do not know but I did look at the ring gears ect when I put a new pinion seal in it.
....I guess I've been told wrong but I've always "heard" there were 3.90's in a lot of the pickups and that it was the later years like the 60's that had even a higher gear???
I'm not claiming or dis-claiming anything here. Just adding to the confusion!!!
I would add for the "doubting thomas" that unless you have a need for a higher gearset, or the rear end is coming from a known, unmolested truck, take the rear cover off, count the teeth on the ring and pinion, just to make sure. I know I bought mine w/o opening it up, and got lucky. My advice if I were ever buying another one, I'd take the 5 minutes to pop the cover off and count the gears.
New here, Was just looking at the talk, I have a 48 3804 9 ft., live in southern Ca. and just had the rear redone out of a 78 3500, that the shop shortened and got some new axels made to fit the wheel base. Not sure of the blah blah to 1 ratio but I can travel at freeway speeds. The 235 with dual YF carbs gets me along just great.