id this rearend

This may help, On my 39 rear diff. there's a flat spot on the bottom with a stamped 9 then a 37, could be a 87. Any way, I was told the 9 on my diff. determined it has the low truck gears. I need to have it changed to 3:54 so the motor purrs above 40. Knowing those stamped #'s may get ya started. LOL
 
39portlander said:
This may help, On my 39 rear diff. there's a flat spot on the bottom with a stamped 9 then a 37, could be a 87. Any way, I was told the 9 on my diff. determined it has the low truck gears. I need to have it changed to 3:54 so the motor purrs above 40. Knowing those stamped #'s may get ya started. LOL
Click to expand...

These numbers are the gears that were originally installed in your differential. The 9 is the number of teeth on the pinion and the 37 is the number of teeth on the ring gear. The 9/37 gear set was a 4.11:1 ratio.
 
Thank's Ross, I could not remember the #'s related to pinion/ring. Now I do. 55Dude, I did look @ your pick, there's got to be some #'s stamped to get ya started.
 
i guess it's a timkin style rear that was also used in studebakers also with really low gear ratio.
 
39portlander, what size is your 39 truck? I have a 1-ton stake I just recently got.
I'm in Mechanicsburg, Pa.
 
that is a Timkin 'split housing spiral bevel' rear on all f2-f3, some f4-f5. standard ratio is something like 4.86. There are guys on HAMB that use two of these axles and other banjo center section to make quick change.
 
Attached photos show the differential from a 1940 one ton express truck. The original gear set was 4.86. I was able to get a 4.11 gear set from Chuck's Trucks. Hard to tell from your photo but I think that's what you have.
 

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Frank Cowan said:
that is a Timkin 'split housing spiral bevel' rear on all f2-f3, some f4-f5. standard ratio is something like 4.86. There are guys on HAMB that use two of these axles and other banjo center section to make quick change.
Click to expand...
that explains the demand for the housing if i decided to change it.:D
 
That's the original rear end. It's identical to the one in the '52 F-3 I did several years ago.. 4.86 standard, 4.11 optional.
 
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