I'm gonna use a Jeff Foxworthy approach here, "Your truck may not be a factory 4-wheel drive if...". The first clue that my truck I assumed to be a factory was an add on kit is the transmission cover plate (1st photo). As you can see it was a combination of torching
and chiseling. Mercifully I did find a cover from AZ on eBay that was original factory NAPCO. (2nd photo) I have taken it for sandblast and powder coat. I will still need to assemble the shifter, linkage and mount to discover if it lines up.