Hi,
I have a factory Diesel Marmon, Another change was to the floor and engine access in the cab. the cover for the diesel is about twice the size of the petrol I guess the Diesel is longer and taller.
there was also a rumor that the steering column was changed but I have never compared the two.
On the diesel the air pump is a stand alone unit bolted to the chassis driven by duel belts from the front crank pulley.
Hope that helps
Regards
Dave