The 8.8 wasn't used until 1983, 82 should be a 31 spline 9". If it is an 8.8, it still should be 31 spline.
And, yes, 83 was the last year for the F100.

 

Someone above said above that the F100 was 28 splines and I would think the car is 28 splines, if so you would be in luck. Just use your old ring gear with the Case from the car and leave your Pinion Gear in. Use your old side shims keep the left on the left and right one on the right. Do not mix them up, that way no setup is required, very easy job, just did two of them. You do not even have to drop the drive shaft. I did check the backlash with a dial indicator and they were both the same as before the ring gear was taken out, the side shims sets the backlash. As long as you use the same housing, shims and ring gear together you should be OK. Use thread locker on the ring gear, lock bolt and bearing cap bolts. Also check the Case side bearings, as you might want to replace them.

If you were asking if you could interchange and bolt the whole Axle assembly up then I would say no.

 

I noticed one time on my 83 F100 that it has 4 leafs on the springs and saw an F150 the same year that had 5 leafs.

 

I hope you are right about both being the same splines. But I looked under it yesterday and it indeed in an 8.8. No tags on it though. But I will probably be swapping R&P on it to the cop car's 3.55s unless it already has some low gears in it...but i'll probly end up getting to set up pinion depth, backlash and the whole works.

 

Save the shims on the pinion, and re-use them, and I bet you will be close. The only reason you would have to reset everything is if the case was machined way off. And that's rare. I would definitely check it, but try what you take out first.

There is a Dana factory a few miles down the road from where I live. Some of the mechanics who worked on the lines have gotten jobs where I work. They were telling me they have an automated system that uses the ring gear bearing saddles as a reference, and measures the installed pinion depth in the case after it's torqued. They said 99% of the time, all cases used the same number of shims, and rarely did they have to pull one off the line because the the normal number of shims would not work.

I did what Subford was talking about, only I stretched my assumptions even further. I had the 31 spline limited slip 3.50 rearend go out of my 1980. I found a good used 3.50 out of an old Bronco, but it had 28 spline axles. The only problem with that is the holes for the axles are too small on the piece that the ring gear bolts to in the 28 spline setup.

I used the bronco pumpkin, took the 31 spline carrier mount out of my rearend, and mounted the good Bronco ring gear to it. Moved the limited slip stuff and the 31 spline spider gears over to the Bronco housing, checked the backlash, bolted it all together, and it runs good, no noise or howling. That was about 7 years ago, still going.