f100today,I have a 28 spline in my 71 which I consider a light duty rear end,can not remember the weight bearing capacities of it but I know it has a smaller axle bearing than my 72.The axle tubes on my 72 look bigger around than the 71 as it is a heavy duty axle.I overloaded my 71 with firewood and overheated the bearing and the bearing retainer to a point where the axle actually pulled away from the bearing about a foot before I got it stopped.Now I always have the shop press on the old retainer after the new retainer and bearing when I have to replace a rear bearing on a 9" just for a little added insurance.
"bowties in the rearview mirror"
1971 F-100 4x4 Short Bed 300 six
1972 F-250 2wd Long bed 390 C6
1973 F-350 SCSpecial 390 C6
1976-F-100 4x4 XLT Short Bed 360 NP435-In-n-out trans case
1977 F-150 4x4 Short Bed 351 NP 435 NP 205
f100today, I have a 28 spline in my 71 which I consider a light duty rear end, cannot remember the weight bearing capacity 3,300 lb. rear axle capacity of it but I know it has a smaller axle bearing than my 72.
The axle tubes on my 72 look bigger around than the 71 as it is a heavy duty axle 9" w/a 9 3/8" ring gear, 3,600 lb. rear axle capacity.
1968/72 F100: There are two different 9" rear axles.
9" with 28 spline axle shafts, with or without Limited Slip, 3,300 lb. Rear Axle Capacity.
Optional H/D 9" with a 9 3/8" ring gear, 31 spline axle shafts and Traction-Lok, 3,600 lb. Rear Axle Capacity.
9 vs 9 3/8: Only FIVE parts are the same as a 9 inch: One pinion bearing and cup, pilot bearing retainer, housing gasket and pinion seal.
EVERYTHING else is different!
The AXLE code is stamped on the Warranty Plate, located on the left door face below the latch.
I have no proof, but it's possible that the 9 3/8" rear axle was standard equipment in the following F100's:
1968/72 F100 Camper Special / 1969/70 Contractors Special & Farm and Ranch Special / 1969/72 Heavy Duty Special.
F250 2WD versions were also available.
Bill / Retired Ford Parts Manager / SoCal Chapter Member / Part number research: 1928/2001 trucks & 1928/89 passenger cars.
Thanks for all the info. I guess I need to clarify something. I am looking at getting a disc brake kit for the rear end. The housing ends where the brakes bolt on are different throughout the years. They have different bolt patterns and shapes. I am not at home to check for myself so I was wondering if anyone knew what style the housing ends are. Generally they are referred as "new style big bearing" or "old style big bearing" or "old style small bearing". You have to know what housing end you have to order brakes. I figured all the 9 inch housings would have the same style ends for these years. So with the info from the above relies being given, if this were just the standard 9 inch rear end; which housing end would it have?
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