EGR, where no EGR before questions

[Duro5341]

Hey guys
I have a 86 K10
HD 350, vin M
TH400 tranny
currently no AIR injection, cat, EGR

My engine does not have an EGR, there is a plate over top of the port in the intake.
Now can I put one on there, and hook it up to the proper vacume?
How much will this increase my gas milage?
Is it just a simple bolt on, and hook up vacume....or is there carb, or engine adjustments?
Where does the vacume hook up?, is it manifold, port, hone vacume?

Thanks for reading
Duro