GMC Repair: which chevy/gmc suburbans actually run?, chevy gmc, coolant

Question
I'm on my third Sub'n. 1st was a 1987, and then 2 1999's (the first 1999 was totaled by a tree falling on it after a few months of ownership). The second 1999 sub'n has has constant problems with the cooling system. Thousands of $ worth. Anything dexcool touches, it kills, apparently. Also have replaced fuel pump 2 or 3 times. Plus many other things. The problem is: I love this truck WHEN IT RUNS! My mechanic has suggested that I get rid of this Sub'n. Can't afford a newer one. I have actually considered getting an older model, from the pre-dexcool years, maybe mid-90's with low miles. My question is: Is there a bracket of model years with Sub'n's that are not plagued with problems like my 1999 model? I don't want to go as far back as my 1987, but it ran way better than this 1999 model. Please advise. (Or could I take all the "guts" out of this one and replace the engine and cooling system with a better year?) Thanks!!

Answer
i would just remove the dex cool and install green coolant, the glycol in the green coolant will kill the enzymes that often cause issues with the dex cool, so if you drain it out and install green whatever is left will be useless and should not cause any issues