Blower motor interchange?

[Zerohour3k]

Here's a question for all you folks who know a bit about motors (or just plain like to tinker).

The blower motor on my 83 300D (w123) is on its way out. I have a "spare" motor laying around from an 84 300D, which sadly is also fairly worn out. Needs new brushes, but the commutator is fairly ridged and worn, so it's probably not worth replacing the brushes on it.

My question is this: Is it possible for me to use a 300SD blower motor in place of the W123 one? I'm talking the actual motor here, not the whole squirrel cage assembly, which I managed to take off. Bosch blower motors for the w123 part number are incredibly hard to come by these days, and are kinda pricey. I looked up siemens 300SD motors, and they're VERY close to the 300D motor in appearance.

So, can I pull the trigger on this, or is there some major difference that'll have me pulling my hair out, or setting my car on fire?
Thanks!