Hi Steve
Do you know if they had a special model number. Or were they simply 1505's.
Some units I've seen on Ebay seemed to have the letter B behind it AKA 1505B.
They were not necessarily the tar filled ones, but not sure on that either. Do you know what those letters stood for at all. Did the tar ones get sold along side the other not tar ones? Or as you said, were they all tar until they moved the factory?
Yes they must have been a pain to ship and install as they weight a ton. I do know the ones I got came from a old theatre in Seattle called the " Fifth Avenue ".
I was told they were installed there in the early fifties.
Mine have the dual brass throats.