Welcome!
That's a really well kept truck with a great color combo.
I'm pretty sure Ralph (ex-Ford parts man) posted the numbers for each of those letters not too long ago.
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.