A further update: While on the road yesterday, it started feeling like it was slipping even more than it had. I checked the transmission fluid, and there wasn't any on the dipstick. Putting a quart in it both cured this problem and also fixed the slipping feeling.

It's getting a transmission fluid and filter change when I get home. The transmission's only got about 35K miles on it; I'd really hate to have to replace it.

i havent drove a blazer in the winter snow ever, but ive had a ranger pickup with 4x4 for the past 8 years. i always like to start out in 2wd just to see how the road really is. then i'll use 4wd if i feel i need it. 4wd can give you a false sence of road conditions. you can go, go ,go. but stopping is the bigger issue. and 4wd wont help with that. in my ranger i run about 300-500 pounds if theres 2" of snow or more. below that the weight of the truck itself is good enough. the blazer is about 1,000 pounds heavier than the truck, i figure 200# in the rear will be good enough. guess i'll find out in the coming months.