4x4 - Different gears front & rear?

[Cap'n Hook]

So I've only used the 4 wheel drive once on my Jimmy in the year and a half I've owned it, but now I think it has different gears in the front and rear diffs.

I locked in the hubs and shifted to 4Lo, and drove down a mile of dirt road to my house. After about 500 feet, I noticed something didn't sound right, sounded like binding or something. So I let my wife drive a bit while I walked by the truck, and noticed both rear wheels would turn less than a quarter turn, then slide forward a bit, like they were locking up, then turn a quarter again, then lock.

The only thing I can figure is someone swapped out the rear gears and didn't change out the front with the same ratio. If the front was a 3.08 in theory, and the rear a 3.42, that may cause this? Maybe? I'm stumped!

The first time I used the 4 wheel drive I was on grass and leaves, and didn't notice this!