I have noticed a lack of fire trucks from the 1950’s era in HO. There are plenty of modern apparatus and vitage trucks, but too many from the most modeled time period. Although after searching hobby shops, train shows, and web sites I have found a couple quality solutions. Lee Town craftsman kits has a B-61 Mack fire truck. Walthers has the same truck, but the kit is more detailed. Sheepscot scale models has various resin kits of different types of truck cabs, bodies, and trailers. They only have one type of fire truck body but it includes hose, booster reel, bell, and siren. You can modify the truck with different truck types, extra fire equipment, and add on pieces to the truck. If anyone else has any advice feel free to add on.
In fact, there are quite a number of 1950’s-era fire trucks currently being offered in HO. Check out Alloy Forms, Busch, IMEX, and Resin Unlimted. What is missing is apparatus from the 1930’s and early 40’s in HO scale. Currently, the only way to get these trucks is to drastically kitbash/marry portions of 1920’s FD bodies with later vehicle frames and cabs.
CNJ831
I have a model i purchased from walther’s of a 1958 open cab seagrave pumper…it’s a kit that you’ll have to put together, but is a nice looking truck and definetly out of the 50’s…my dad was a professional fire fighter and he was assigned to a truck similar to this one only it was a ladder truck with a tiller seat…chuck
Hers a couple of shots of 50’s era rigs on my former layout. 
