I just replaced all my capacitors on my Armstrong TR21-12, here are the values of the originals.
Compressor: 30MFD 370VAC
Blower motor: 7.5MFD 370VAC
Fan Motor: 7.5MFD 370VAC
Start capacitor: 21-25MFD 250VAC
Here are the Grainger part numbers
30MFD 370VAC, #2MEC9
7.5MFD 370VAC, #2MDV6
The original "compressor", "blower motor" and "fan motor" capacitor was one unit. I don't think they make such a beast today, so you need 3 different capacitor to replace the old 3 in 1 unit.
Parts needed: Fan for roof vent or whole vent fan assembly, vented catalytic heater.
My blog for the 1975 Tradewind restoration
, Has not been updated in a while but I am still working on it.