Hocmann

Well I'm having a bit of an issue with my timing on my pickup. I have an 87' Pickup standard cab w/ 129,000 miles on it. When I bought it in July of 13' it needed a valve adjustment, and couple of minor things to make it run better. Since then this is what I have invested:

Cap and Rotor,
Plugs and Wires,
Air Filter,
New hoses

Now, the previous owner really didn't know what he was doing...
and I have had to fix a lot of what he messed up. He took the air pump and the A/C off.. and was somewhat jacked up, but most of the vacuum lines are there. When I did the valves the guides and the chain seemed to be OK..

Now - the issue: I live in the mountains @ about 4,500 ft.. I know you can set your timing to 2' farther to accommodate, but when I hook up my Vacuum Advance @ 0' I get detonation. Knowing this, I went and purchased a new Distributor and installed it. It was a remanufactured from Autozone, and it didn't work!
When installing, we put it at TDC, and made sure it was at cylinder No. 1. Pulled out the old one and put in the new one. Took it for a drive and retarded it back as far as it could go, still detonation. So, we took it out and went back a tooth, and it was then TOO retarded. There wasn't any middle ground, so we came to a conclusion that it had to be the distributor. SO... we took it back, and here I am: What could be the issue? Bad distributor? Vacuum line that I am missing that could affect my timing? (The lines that run from the Carb are blocked off due to being too advanced when at the current timing degree) I would appreciate the help. Thanks, Hocmann