Quick question: Ford part

I recently picked up a 9" disc brake rear end and would like to get an idea of the ratio.
The ring gear has this stamped on it czaw4210-a (heart) 2.
The problemis, I can't find any matches when I search on that number on the Ford sites.
Any ideas?
r

 

If you can see the ring gear, count the teeth, count the teeth on the pinion. divide ring by pinion. that's your gear ratio

 

I couldn't see the pinion gear, that why I didn't do it that way.
All I could see was the ring gear. I guess I should have counted the teeth anyway, but I've already installed it into the casing.
r

 

IF ... the gear ratio is the one from the factory ... and the disc brake setup is factory ... then the ratio will be a 2.47 / 2.75 / 2.79 type of ratio. Which car did the rear end come from originally ?

The small Lincoln Versailles ( 58 inches or so wide ) came with the 2.47 most of the time.

 

Also, the ring gear number is not in the catalog because it is never sold without the matched pinion...try searching the set number, 4209 probably, with the same prefix and suffix stuff.

 

Turn the axle while counting the revolutions of the pinion shaft.

 

CZAW is not a proper ford part number, is it really C7AW?

and yeah, count the pinion turns to get one ring gear revolution. That's about as easy as it gets.

 

According to the correct parts number (thanks squirrel) it's a 2:75.
Oh well.
Thanks.
r