1996 Chevrolet 305 1/2 ton

I have a K1500 1996 Automatic 4WDQuestion;  The vehicle just quit like it had been put in neutral at 70mph didn't make any clanks or grinding.At the shop it had to be pushed in.Upon further investigation I was told they engaged the 4wd in Low and the truck would move.1st question is if the chain came apart( w/o any noises) then how could it be a drive chain and still move and can this issue be somehow rerouted around the transfer case w/o having to be sold a rebuilt one because I'm 600mi from home on a holiday?Answer:   It sounds like a range fork issue… the transfer case range fork is worn allowing it to come out of high range but still shift into low range… unfortunately the transfer case would have to come apart to fix this or install a rebuiltIs this electric shift or manual shift transfer case, give Scott a call toll free 888-824-2012 he can help you.