Has anyone had the problem of front or rear axils locking up and skidding tires, my 1991 Silverado k1500 5.7l 700r4

We're going to need a little more detail. "Locking up and skidding tires" like:

- You're driving along and singing a song and suddenly one or more tires locks up movie-style? If "yes" to this, something terrible has happened.
- Tire on one side of axle locks to the other side? If "yes" to this, perhaps a differential seized up (open, locking, or limited slip, doesn't matter). This is unlikely.
- Front and rear axles appear to be tied together such that any cornering creates a bind between the front and rear tires and on dry pavement make ongoing small skidding or scratching sounds? If "yes" to this, it appears you are in 4WD and you don't expect to be in 4WD.
- Other . . . . ?

Yeah, what ^ said.