Stamp on my rear end

[jd2ksilver]

Thank you, next time its up I will try it and see. 

[David Pollock]

The 39 is likely the number of teeth on the crown gear. As the pinion has 10, the ratio is 3.9 to 1. As for the F, I have not seen that before.  With one wheel still on the ground, rotating the other wheel will turn the driveshaft  1.95 ( half of 3.9) turns because of the action of the spider gears. Rotating the wheel twice will give you the correct count.

[jd2ksilver]

Thanks, will try that next.

[Jim Benjaminson]

Should be.  Easy way to confirm it.  Jack up one rear wheel - place a mark on the driveshaft and have someone turn the wheel one complete turn.  The drivesshaft should have made 3.9 turns in
the same time frame....

[jd2ksilver]

Hey all , been awhile since I have posted here.

Question, on my diff I have 39F stamped on the top and bottom.  Does that mean 3:9? 

Its a 52 P23 and I understand they came with the 3.9 with a 4.1 as  option in hilly states.

Any clues?????