Trucks hold their resale and always go for big money vs cars of the same maker and year. OP after re-looking at your listing I dont think he is that out of line, even with the miles, because how many LIKE NEW, rust and dent free, 1995 pick up trucks are you going to find, with all the other stuff he has put on that is a Z71 4x4?
Yes you may find some cheaper with less mile, that have rust in and out and all around, but he seems to have a mint truck on his hands, aside of the engine miles, and frankly GM parts are cheap and replacement engines are even cheaper then anything else on the road. Just my opinion, you want good, you have to pay for it, you want crap, go find something else that is cheaper but not near as nice looking or rust dent free. I know for a fact if you took that rust free truck he has to Chicago you get close to half of what he is asking for it. Lots of people in that area would die for a rust free older car in near mint condition and pay out the ass to get it.