4x4 cuts out

[allformike]

so the other day i had to use the 4x4 for more than a few seconds to get myself out of some snow. but this morning i went to a friend of mines house and the road looked like it hadn't been plowed for weeks. i stopped and put it in 4 high while in nuetral, put it in reverse, then in drive and it went in good like always. as i got further down the road, i began to slow as the snow was nearing my bumper, gave it a little pettle, then a bit more then CLUNK and no more 4x4. i put it nuetral put it back in 2 wheel, waited a second, then back to 4 high. it worked fine untill i got about half throttle then it pops out. so i'm thinking that the hubs may be gone, or near there. i have no idea if they have been changed and the truck has 277,xxx miles on it. also is it possible to change them to lockout hubs? what you guys think.

[wade-ve7trw]

check this out:http://www.4x4posi-lok.com/inst_tsg.html. temperature related problem with the engaging thermal gas actuator is a common problem of your year of truck. Search posts for more info on this.