Is the stub the oil filter threads onto long or short, see picture. IIRC the long is to 1990 with metric threads, the short is 1991 and up with standard threads (in the 4.0 anyways).
Here’s the Google Earth street view, the first one was back in 2011 when they caught me mid engine transplant, the second is the most current, and the third is a doctored overhead shot.
Nice! Don't forget the cargo light and those are the factory bed rails.
This is currently the earliest produced 1988 MJ in the Registry.
@Classy Comanche add yourself to the original owner's thread, since it was your great grandfather's I think it qualifies.