In preparing to do the floor pans, there are some items I need to remove from the firewall. One of them is the Heater Box. It is a 3 piece box, with a largest section bolting on from under the dashboard on the passenger side.
The Blower motor & blower motor housing are bolted on from the outside of the car on the firewall.The remaining 4 bolts that hold the large heater box section under the dash also hold the blower motor housing to the firewall. So I had to remove it first.
What a surprise! A Mouse nest! I can’t remember when the last time was that I ever pulled an old car apart and didn’t find a mouse next somewhere inside of it.
Last was the Heater core & it’s metal housing. Now that these are all out, I can start cleaning the toe board & floor pan up and get to drilling spot welds , cutting pans and prepping to weld in those new pans!
Ranchwagon's Blog 
Looks like it’s a pretty straightforward removal – one good thing about old cars, not a ton of stuff you have to remove in order to remove the thing you need to get out.
You’re absolutely right. This was the easiest heater box assembly I have ever removed on a car. Other cars I have worked on, involved removing the dashboard and was very involved.
3 cheers for 1950’s basic mechanicals!
Doing a Heater box removal on my 1958 Edsel Bermuda Wagon and using your site photos and info, Thanks! Hope you continue your project, your doing a great job!