Here are two that I was able to find regarding the vacuum lines. Both are for the 4.3L V6. The 3rd one is for the HVAC system. NOTE: These are general diagrams from GM. If you have a different routing diagram under the hood, follow it, but I will assume you don't have that.
If there is something specific or a specific area that you need, let me know. Also, (I don't know if this helps) but you should have around 12psi vacuum at the intake at an idle. If that is low, you have a leak. If you maintain that and still feel you have a problem, don't look for disconnected or broken hoses, but rather, look for kinked or collapsed hoses.