Hey guys, I need info from ya, mostly just for curiosity sake..... I'm working on the old 49 F-1 and I finally got to work on the rear differential, removing years of grime and crap off it. I looked at some older post trying to figure out what rear end this is and I came to the conclusion (I think) that its a Dana 41. In the upper left hand of the center of the axle it reads 16429, upper right is a US patent, lower left is a US patent and lower right is stamped 41. It also has a tag bolted to it that reads W 41/11. On the right axle it looks like a stamp that reads 6649A, but is more or less fades toward the "A" and is hard to read so I may be wrong on that one. Ideas???

Thanks!! Will

 

Indeed a dana 41. And with the rather rare 3.73 gear ratio to boot. On the passenger side axle tube, you might be able to find a date code stamped on it.

 

Thats where I got that "6649A" number but it was hard the read so I wasn't sure if that was a 9 or an A.

 

A could be an R? June 6th, 1949.

I wonder if after the date stamped, if there's a simple sequential build number/letter.
Here's my spare dana 44:

 

OK, I just went out for another look. This time with my reader glasses AND a magnifying glass. It is definately an A. What did the letters at the end signify?

 

I believe 3.73 was the standard ratio with a V8 up til '50? At which point they geared down to 3.92 as standard. That's why manure spreaders race away from the monkey faces at stoplights!

 

But we get you on the top end! I've got FOUR Dana 41's. All of them have the 3.73. Only 2 are attached to trucks. You want one!?

 

The shop manual (the reprint w/52 supplement) only lists 3.92 and 4.27 gears, that's what I was going off of, but I remember someone talking about 3.73's being an option? Each of my F1's had crashbox 4's, 1 6 cyl, 1 v8, and they each had 4.27's. I'd be pretty happy 3.73's, though.

 

Havi, a few years ago, some guys (I'm pretty sure it was actually Ross) pointed out that there is a misprint in the shop manual. Apparently there's another spot in the manual that correctly lists the 3.73's.

 

My 48 F1 had 4.27 gears. 0-45 was really fast but then it just stayed there.

That's why I swapped in the 3.50 9". I'll give you light-to-light in exchange for hwy speeds.