rear end ratio

[len]

How can I determine what rear end ratio I have? Thanks

 

[alanwoodieman]

look on bottom web of the rear end--there should be two numbers, that will tell number of teeth on ring and pinion
34-9 3:78
37-9 4:11
39-11 3:54 sometimes you have to look real close, maybe run a scraper of the we

 

[19Fordy]

If the rear end is in the car do this:
https://www.earlyfordv8.org/forum/printthread.cfm?Forum=18&Topic=8717
If the rear end is out of the car do this:
https://www.youtube.com/watch?v=bkvp3Fq21ZM

 

[39wagon]

If you have a tach, you might try this site:
http://www.advanced-ev.com/Calculators/TireSize/
You can enter three of the four variables (tire size, rpm, rear-end ratio or speed) and it will calculate the forth one for you.

 

[RalphG]

If you happen to have a 52 Mercury car, like mine, it is stamped on the back of the axle, passenger side. 3.31