This is a very interesting thread to me.� I also acquired a Harrison Heater that needs restoring and, as with many things, more information is good!�
From garage gnome:
I don't know how many people actually know this but there should be rubber grommets between the firewall and the heater core tub brace on the back of the heater. The left is an original and the right is what I replaced them with.
I have never seen nor heard of any surviving documentation on these heaters.� I've been fooled before thinking I was looking at original when it turned out to be a PO addition from 40 years earlier.� This grommet is interesting - and I like it.� It would obviously help isolate vibration.� �Where did you get the replacements from?
From Ryan_M:
I made the same connection on the head but took a different approach on the water pump.
I don't have a Parts Manual (PM) covering the 3A but wonder if y'all could check to see if the fitting matches what's listed for the 3B:
GROUP 35-21 - HEATER AND DEFROSTER
664971� �� 1 Elbow, heater, 45 degrees
I polled some 3B members that had an original heater and apparently that 45 degree fitting was attached to the pump.� Mine originally had a straight fitting but I like the idea of the 45 degree fitting as it seems to clear other components with room to spare.
From athawk11:
This is another detail you might find on a Harrison installation. This is a heater hose bracket.� It was mounted to the passenger fender�
This one also stumped me at first sighting over on the vernco.com site.� Again, checking the 3B owner's, they showed the same bracket:
669733� �� 1 Bracket, support, hose
Now knowing that the 2A, 3A and 3B used this bracket I'd assume it's the same.�