Mark,
I was the source of the headlight info...glad that worked out
The easiest way to check which chassis is to look at the steering wheel emblem.
The 7400cc (454 cu in) V8 engine probably makes it a GM (Workhorse) vs. Ford's RV chassis for 1996.
Using that year, you can start your search for the part as being from a GM/Chevy truck.
Or you could PM an iRV2 member named DriVer and ask about the part. He (Mike) is a Workhorse Guru.
Best luck