Worm gear upgrade???

[brak]

I have a 93 K1500 silverado i picked up a few months back.
At the time of purchase, the PO was telling me everything he had done to the truck, and mentioned that he had done something to or with the Worm gear.

Now i'm a big gearhead, but the inner workings of the transfer case are a mystery to me.

Today we had the first real snow of the year, super slippery, heading up a hill, so i reached down, locked in the front, and It locked immediately, no lag, no noise, front wheels spinning the minute i shifted back into drive. you should've seen my face... I swear my jaw hit my lap

ive had a few of these trucks through the years, and driven a hell of alot more, and I've never seen the transfer case lock in so quickly and with such ease. I'm used to the sloppy factory lockup, surging, waiting for it to lock, watching the light flicker, you know the drill.

now i need to know what was upgraded, because I'm doing it to the next one of these i own.