2001 Chevy Blazer Head Gasket

Dealer? Why Dealer? Plenty of independent garages that can do this.

Don't jump to the conclusion of a headgasket, it can be diagnosed. I have seen situations where a very minor leak can cause a slow drop, slow little of a leak that it isn't seen on the ground, but may be burned off on a manifold for example.

It could be and intake gasket (4.3 motor?), That isn't much of a leak. Not to discount it. I would start looking around for a light pinkish drien substance that may be at any point where coolant travels through. Maybe a seapage at a hose around the heads, intake etc.

Sometime too some system like a level that is a little different than what the bottle says they should have. If you don't see anything, don't add anymore and see if it continues to drop after another month.

The reason I ask about the dealer, is prety much what I expected you to say. I'm not saying that you're right or wrong, but as long as I have been in this industry I can say that it is not necessarily true. Dealers pay on flat rate and service writers work on commisison. Both of these can be bad for a customer. Any shop, dealer or otherwise is only as good as their techs and the ethics of the company. I'm just saying that you can get high quality work done ethically at an independent shop. All of them. Of course not. Dealers in my area are scary.