i've read that up to 72, the f100 rear 9 has a 61" WMS... and it has 28 splines but big bearings. after 72, was the WMS 65" like the other f150 or bronco?

brandon
my plans are to swap it a 9" into my XJ, i just need to find the right one...

it was my understanding that the bearings on stock 3rds are 2.89's unless you are running more then 31 splines. in other words.....28 and 31 splind are 2.89's.

also if the rear came from a 4x4 then you will probably be 31 spline. for the 28 spline your guess is as good as mine. I would pull an axle and count just to make sure.

the housing shape will tell you alot also.....if it is a banjo housing it will be a toss up on weather it is 31 or not. the banjo is the earlier housing and that is were the 28's were used. if it is the larger centered 9" then you are probably going to have 31.

all this info is good indications of what to expect but the 3rds can be swapped so unless you pull an axle or the 3rd you really just have a shot in the dark.

also look at the castings on the 3rd......if it says "WAR" any where on the 3rd avoid it like the herpies.....that is the weakest housing.

The only true 100% accurate info for a 9 inch is your tape measure.
Ford did so many changes and want not, just hit the junk yard with a tape measure and fine out.
Yes, Some 2wd F100 had the 61 inch 9

Not ALL truck 9" axles came with 31 spline. The 9" i got was 28 spline.

If you can find one, a 78 or 79 bronco is a great donor for axles. My freind and I both just did this swap. They both had 31 spline shafts and big bearings. We both opted for 1.5" 35 spline cromo shafts from dutchman. Mine is in a xj also. They best part is that if you steal the front hp44 the axles don't look out of place imho. There is no comparison between 31's and 35's but it does cost a bit extra besides just the shaft price. You have to get new bearings and also a new center section. I can tell you though that This is the one part I will never fear to break on my rig.