[Model51]

The answer to your question regarding the towing capability of your truck can be calculated with information found in the 1941 Ford Dealer Showroom Album. There's a table listing the Gross Vehicle Weight Rating (GVWR) for your truck based on several equipment choices. You will need to know exactly which spring set is installed on your truck, the current gross weight of your truck, tire sizes and maybe a bit more to be able to calculate the maximum GVWR.

Back in the day, pneumatic brake systems were installed on the truck and trailer to provide safe stopping power. Old time pictures show massively overloaded trucks pulling heavily loaded trailers, but that was before regulations, modern traffic and a bit less concern about safety. I bet some of those loaded trucks never got faster than 15 miles per hour with those loads.

You will still have a relatively weak engine pulling all that weight and everything needs to be in tip top condition. Also, be sure you check you state motor vehicle requirement for weight classes and driver licenses.

Based on the picture of your trailer, or one like it, I'd recommend a modern diesel engine truck to haul it around and enjoy your fire truck as an antique fire truck.