Common vendors and dedicated replacement funding go a long way to ease fire truck buying.
If you work for a department that purchases apparatus on a recurring basis, keeping the process simple and consistent can pay off in the long run. This approach offers more than financial benefits. One additional advantage is the familiarity the emergency responders and maintenance personnel will have with the new purchases. And established contacts can be maintained with apparatus vendors and parts suppliers. In short, the objective is to not reinvent the wheel.
The specification process can be long and arduous. If you have a well-designed, functioning apparatus in service, using it as a template for future acquisitions can save substantial time in the planning and pre-fabrication process. It may even help speed up fabrication.