VCCA Home Forums TECHNICAL - GENERAL Trucks and Vans 1955 1st series differential number

Tore off the rotted plywood bed and got in and cleaned off the differential yesterday. (Cleaned up myself afterward and still finding grease spots!)

Stamped in the front side on the left (looking from the tranny side) is:
NK 10 27

Does this really mean I have a 2.70 rear end?? I've driven it and it for sure does not act like a 2.70 should, so I'm pretty skeptical. What is the gear ratio of my differential?

Thanks,
Lyn Gomes

I can find the code/ratio info but if its the original for a 1955 1st 1/2 ton truck it would be a 3.90....They never made a 2.70 back then.

Yeah, kinda figured that would be the one. Thanks for your help.
-L

I took the differential out over the weekend. Before I took it out, I jacked it up, blocked one of the wheels, and spun the tire while counting the revolutions that the driveshaft makes. I turned the wheel 10 times (to get a more accurate number) and the driveshaft turned 19.5 times. This gives a ratio of 19.5/10*2=3.9 (multiplied by two because one of the wheels was blocked).

Also counted the number of teeth on the pinion - yep - it is a 3.90.

When scouting around on the web, I found some specifics for other diffs made around the time of my truck. Sorry, can't remember the address of the site.

The first letter - N is the gear ratio. N = 3.90

The second letter: K, refers to where it was made. I don't know where it was made.

The last four numbers are the date it was made: 10 27 = October 27, just shy of my b-day.