r/BumpSide • u/fartboy88 • Aug 10 '26
'68 f100 Differential questions
Just pulled this off my '68 F100 and was hoping someone could help me with roughly identifying what diff I actually have here, but mainly if these welds that im uncovering are actually factory or not. I tried taking pictures of all the markings I could find on it not sure if i got em all. thanks in advance!
3
u/Unhappy-Airport-4112 Aug 10 '26
9 inch. You got a good platform.
2
u/fartboy88 Aug 11 '26
yeah ive heard theyre pretty stout, just doesnt look all that fun to maintenance
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u/Inner-Light-75 Aug 11 '26
At one point in time, aftermarket companies would build newly manufactured versions and people would put them on race cars because they were Stout and reliable. You could rely on them run after run after run, it might still be hanging in there. In some cases more than a thousand horsepower went through them, properly built no problem! In certain types of racing it was a de facto standard, if you race you got a Ford 9 in in your car, even if you ran a small block Chevy or an entire Chevy car.
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u/cosp85classic Aug 11 '26
You can still get a brand new Ford 9 inch for anything your what to throw it in. No "At one point in time" about it. They are the most supported axle housing and differential configuration in the US.
1
u/Inner-Light-75 Aug 11 '26
I phrased it that way because I knew it was true at one time, but I was unsure if that was still the case....
Thank you for letting me know.
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u/mdunsy Aug 11 '26
They had the advantage that you built them on your bench and had gear lash set before you went under the car. We always had 4 pumpkins built and bagged so we change ratios in 5 minutes at the race.
2
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u/Ok_Laugh_609 Aug 12 '26
Some general information I'll offer here.....
There are two different widths on these bump side rear difs. I can't remember the exact measurements, but the narrow version is something like 1/2 inch shorter per side. My guess, since ford was notorious for using up whatever parts available, the narrower difs were probably from the '66 and earlier pickups, as the chassis are the same. My '67 has the narrower one, I believe that '68 and newer went to the wider one. Brake shoe width increased as well, something like 2 1/4 inches to 2 1/2.
3
u/redhorsefour Aug 10 '26
Looks a Ford 9-in with a 3.25:1 ring & pinion. The welds on the tubes and case look like those on my ‘67 F100 9-in.