1953-1956 F Series Trucks may have either a recirculating or a fresh air heater core.  All trucks were plumbed to a vent however the recirculating heater core box blocked off the vent and the heater core is visible in the cab.  The Fresh Air box had an open vent and enclosed heater core.  Recirculating heaters were less expensive but cannot draw outside air and cannot control of how much air is divided between the defogger and floor heat.

 Other information that may help identify your heater core/heater box

• 54, 55, 56 had the same heater box
• 53,54,55 blower motors were 6V, 56 were 12V
• 53 pulled the fresh air from the louvers on the cowl, not from the front of the truck
• 53-55 defroster hoses go over further towards the driver's side and uses 1.5" hoses
• 56 uses 2" hoses up to defrost duct

Tube designs vary so please please please compare your tubes when ordering.  We refer to them as Models A-D. Please confirm the tube path before ordering. 

Present Lead times.

Made in the USA.