Telltale signs of original type of engine

[Mack B]

This is something I’ve been curious about after I’ve learned some details from this forum, and purely for entertainment as I know anybody could have done anything in the last 56 years.

After I acquired my 63, I checked the casting number and going by that information alone determined it may have the original 283 in it. It’s obviously molested, but I had no reason to think otherwise until I noticed orange paint flaking off the bellhousing revealing green paint.

Assuming the bellhousing is original to the truck (and that’s original green paint) that would mean it had a 292 right?
Did the 6 cylinder trucks have different throttle lever arms or anything else different from V8 trucks that would be a clear giveaway?