Heater Box Non Ac Question

[uk72step]

Hi Guys,

I am stripping my 72 Stepper down for rebuild. Whilst doing this I noticed the bakelite?? Heater box in the engine bay is cracked in one corner. Is this heater box common to other years, later trucks or passenger cars? Truck is Non A/. I'd like to get a replacement but obviously the parts are scarce over here. 73+ trucks are more common and I weas wondering if the heater box for these was a common carryover?

Cheers
Lee