A Muscle Car Research Exclusive!
Muscle Car Research is proud to offer a brand new reproduction of the Ford C9ZA-19C624-A washer that was used to support the firewall mounting points for the heater core and air conditioning evaporator box assembly on 1969 and 1970 Ford Mustangs (and possibly other vehicles). This is a 100% accurate reproduction of the original Ford part that was made to Ford's original design specifications, from the material (Hot Rolled Low Carbon (HRLC) steel), to the dimensions (2.25" outside diameter, 0.31" inside diameter, and 0.060" thickness), and to the phosphate and oil finish. Two are required per vehicle, so your purchase here includes a complete set of two washers.
Please note that C9ZA-19C624-A is the engineering part number for this washer, not the service part number. I haven't been able to find the associated service part number. That could mean that the part was never sold as a service part by itself, or it could mean that my reference material is incomplete or inaccurate.
Here's what the washer looks like when installed (the second washer is installed on a stud towards the center of the firewall):