Update: while reading David Doyle’s G506 book, I noted that all original G506 engines were painted OD green. My engine is a bright GM orange. Looking over many pages of data on the internet, I found a site that lists certain numbers cast on each type engine. Here’s the site: http://1954advance-design.com/Stovebolt-engine/casting-numbers.html. In short, what I have is a 235 cid motor which was used on 1954 trucks. The block was also used on trucks and cars in 1955. That explains the shiny orange paint job. This adds to the difficulty of how far to refurb the truck. I just don’t have enough parts to make it 100% at this time. So, make it work is probably what I’ll do. It’s still going to be a fire truck, regardless.