4x4 problems

i was wondering if all of the chevy front differentials on 4x4 trucks had posi or if some are open differentials. the reason i ask is that i seem to remember my truck being able to spin both front wheels in the past, but i am not completely certain. i took the truck to a shop to get the fluids filled and they say they filled the front differential. would they have possibly forgot to add the GM additive for posi-traction? right now it only spins one front tire, which sucks because the rear end is also one-wheel-wonder and basically the 4x4 isnt helping out much at the moment...

I don't think any came with a posi in the front. The best thing for snow is good tires. Uneven load will cause one to spin and not the other. It could be anything from a weight difference side to side or one caliper is draging.

I actually beat a 4x4 Silverado with my Beretta to 30 MPH in a couple inches of snow (GoodYear Ultragrips)... the jackass thought he had a chance with "touring" tires.