msd 8910 tach adaptor with mp dist

Just got back from the machine shop here(friends of mine and fellow mopar junkies but alot older than me so I figured they would know more about it) they both seem to think that the adapter is needed, if so what is the exact issue? what wires to tie into or what wires go where or??? and what msd box do you have, I have a msd book that has diagrams for bout every combo of components they make being used together so I should be able to figure it out.
Lemme know,
Jr.