Don’t know the bodybuilder but the ladder is on an Oshkosh chassis. After dropping out of building municipal fire truck chassis, Oshkosh later bought Pierce, which is now one of the US largest firms, and also built the first American hybrid electric fire pumper. They did continue though to build very impressive airfield crash trucks, loads of examples of which can be found on this site.
Added by Rob Johnson on 29 September 2022.