I drove across a river in my 1995 Z71 that was much deeper than when I drove across a year earlier. Went into a hole that high water gouged out. Not reckless. Just much deeper than expected. It is amazing how much water a V8 will hold... and both axles. transmission, transfer case and fuel tank! Long story short I had it running the next day after I drained everything and dried out the computer. EVERYTHING was submerged. Only casualty was the lumbar air pumps.
Fast forward ten years later. I bought another truck, the one in my avatar. Several years newer (1998) but same buckets and interior. Pumps didn't work in it either. So I pulled them all out, all four, and carefully disassembled the motors from both my babies. The 1995 pumps have a slightly different motor than the 1998, but quite similar really. Seems all the motor bearings were seized. All I had to do was gently loosen and lubricate all the motor bearings and reassemble them. Now they all work!
Wasn't a big challenge. Take your time and be careful.