John, Your best bet is to find another 35 truck to use as a pattern/guide to rebuilding yours. I've been collecting 1935 Chevrolet literature for over 30 years and have never seen anything showing wood patterns or how pieces were assembled (car or truck).
The fire body will be just as hard to find info on as many Chevrolet trucks were bought by small fire compamies who were on a tight budget. They hired local coach builders to fabracate a custom body around a Barton or Hale pump.
Wish I had better news...
Mike B
