Started to clean up and inspect the rear end in my '50 F-1, which I thought was original to the truck, and found the tag with "W 51/13" attached to one of the cover bolts. If I understand this correctly, that would indicate that it has a 3.92 gear ratio. The shop manual says that the '50 F-1 with a 3.92 ratio is setup as 47/12. Does this mean that the rear end is not original or was the 51/13 setup something that didn't get into the shop manual? Does anyone else have a similar rear end or have any idea about what it might have come out of? If the ratios are the same would the higher numbers affect performance in any way?

I did a search and found a discussion in 2008 started by Propane32 about the same topic but there wasn't any conclusion about whether it was original or if not, where it came from.

 

AFAIK, dana 44's replace the dana 41's mid year of 1950. So is it possible the gears, though ratio is the same, could have changed between the two? Look on the carrier housing for a 41 or 44 to see which you have.

 

Thanks for the information. I'll check it out.

 

I have one of each, too, and can look at their ratios if needed.

 

Looks like it's a 41. Attached are some photos showing all of the numbers I've found so far.