I got this rear the other day from a "junk" yard...it was cut out of a '57 f-100..
the tag reads 3.70, I can find any info. on what that means,...I'm guessing it's the gear ratio? What do you guys think......oh yea, it looks like a perfect bolt in for my '49 f-1 rear swap.....

 

Maybe the early tags were that simple....but more info than you want here, including tag pictures about half way down:

Ford nine inch differential cases +

A little WD 40 will clean that right up.....

 

3.7:1 is the gear ratio. That was pretty standard for the 57-60 9" rears. That is the same as the one in my 60. It is also a pretty common swap into the 48-56 trucks. That is a 9" rear and it is easy to change to a different ratio by changing the center section, commonly called a "third member". If memory serves it is a 28 spline, so any 28 spline Ford 9" third member will bolt right in that rear end if you want to change the ratio.

 

I forget? But wasn't 57 the first year of the Ford 9inch?

 

yes, to my knowledge, 1957 was the first year Ford made the 9'' rear...
the '57 f-100 9" bolted right into the '49 f-1 , spring perches lined right up...may have to shim it to get the pinion angle at 3 or close to 3 degrees....putting new seals in her now....also redoing the brakes

 

You're lucky to find it. Sounds ideal with that width and all.

 

here's a pic of how the spring perches fit, and my home made shock mount, used a old socket among other things......

 

actually all rearends from 57 - 72 in the F100's were the same width and perch location, so you are not limited to just 57 - 60. the early rear ends (57 - 60) are considered the weakest rear ends due to the 3rd member being a weak casting and the tubes are just butt welded to the center section. the later rearends (proably 67 to 72) had the stronger axle tubes splice welded to the center section and the stronger 3rd memeber casting. also if you look for a camper special F100 from 71 or 72 with a 390 (maybe even 68 - 70, but i know 71 and 72 for sure) good chance it has 31 spline axles in it.

just some info for you in case anyone is ever looking for a rear end.

rgds
Mike

 

Thanks. Good to know. I probably new that at some point , but my little brain doesn't hold so much and I have to keep notes and articles for most everything. Especially items like this.

In my truck I've got an aftermarket narrowed housing with bracing and a Strange Center Section with a locker and 35spline axles.

So there's lots of options, and still its all the 9inch family.

 

Camper Special, Contractors Special, Farm and Ranch Special:

1968/72 F100: Ford offered a H/D 9" that has a 9 3/8" ring gear, 31 spline axleshafts and Traction-Lok.

Only 5 parts are the same as a 9 inch: One pinion bearing, one pinion bearing race, pilot bearing retainer, housing gasket and pinion seal.

EVERYTHING else is different!

1957/67 F100 use the same R/L axle shafts. 1968/72 F100 9" use different 28 & 31 spline axle shafts, as the rear brakes are larger (11" x 2 1/4").

 

Good to know/interesting stuff/thanks Bill