Just got done with our first mountain pass tow with the new 383 stroker. It's amazing, huge power increase over the 350, charged up the hills and pass mostly in 3rd, 2nd gear on the last climb over Stevens Pass. Had a fully loaded 28' Trail Cruiser and the Suburban weighs 6,000 lbs just sitting there. Cruises in 4th on I-5. Trans stayed cool, have a guage. anyway, the purpose of this post is a dumb question. The '94 GMC is a 4 wheel drive (K1500), I've never had a 4 wheel drive in my 74 years. Does that mean it has positraction? I was backing the trailer onto some leveling blocks in gravel and the rear wheels spun and dug in. I was surprised to see that both rear wheels had dug in. I did put it in 4 wheel to get the trailer on the blocks.