Well the red flex circuit clusters are different than all the later green ones.
But diesels were available in central and south america.
So I would assume those clusters had diesel tachs and glowplug indicators.
Otherwise maybe switching to the later dash?
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.