M1078 Frame Width?

[Aardvark7]

Does anyone know the actual frame width of the M1078 (4 wheel model)?

Wondering if I can mount an ambulance box on one of these (it's a big box, 14' long, underneath is up to 43" wide). Box came off a Freightliner FL60.

Does anyone know? Thanks in advance!

 

[Oxyacetylene]

The frame rails are 32.5", measured to the outside of the C channels. The C channel is approximately 2.5" wide.