I hear what you are saying vombil and I bought it as a maybe, at the price will be worth the shot. I just havent looked too far into it yet to I believe say it is or it isnt. I have found the footwell lights and traced them back to the harness and they are not spliced in and had a look at the light harness and seems the same. Working hard on replacing the roof in the 73 308 HQ van so been sworn to not touch the HZ till the HQ is in primer.
You state the point I am trying to make exactly, you bought 18v so as to be sure it is a sandman, if it wasnt it would be a big maybe.
Unless it has those unique sandman indicators it will always be a 95%-99% thing.