GM-GMC: installing a tach, pig tail, stock vehicle

Question
QUESTION: i have a 1991 2500 suburban and i want to install a tach. i need to know how. also, my trailer lights arnt working. i need a wiring diagram. can you help?

ANSWER: What engine do you have in your suburban?  As for wiring diagrams.  I have no electronic service information for a vehicle that old.  It will be after the new year when I am back to work before I could scan a diagram and forward it to you.
Thanks

---------- FOLLOW-UP ----------

QUESTION: i have a '91 350 tbi

Answer
I found this on a site for you.

Providing that you have a stock Vehicle ignition system, we just put a tach on our 90 350 and there are two plugs on the coil, a single wire comes from the fire wall, the other has two wires and comes from the dist, out of that plug there is a short wire pig tail that is just hanging there and it has a protected male terminal on the end of it , plug your applicable tach sensor into that connection and follow the tach install instructions to hook up your lighting and ignition wires. Most new tachs come with installation instructions. Happy Reving


If that doesn't do it for you let me know and I will get into it with more detail