radiator core question R2

I have been working on the radiator core of my R2. On the bottom of the core where the hose elbow attaches, was leaking.

The question is, how is that elbow supposed to be attached? It fits right up on the bottom of the tank and has 4 holes in it and also holes in the tank. It looked like pop rivits about 3/16. Is/was there a gasket or seal of somekind there? The parts book only lists the core as an assembly.

I am pretty sure that it will be repaired with some sort of sealer and new pop rivits. I was just curious if any body knew how it might have been originally? I would have taken pictures but didnt think of it until the core was gone to be looked at by another.

Which series/ serial number R2?

4J 1098 Electric start. but has crank still

The elbow assembly is attached to the core assembly with two cap screws, S-1594 and gasket 4B5663, the iron flange that this is bolted to is part of the core assembly and is soldered onto the brass core/lower tank.

The radiator assembly is very similar to the one on the J model D2 of the same era and could have been switched, also I have seen many of those style radiator lower tanks modified to accommodate pump or pto shafts off the crankshaft.