Ok, guys, let me put that question to rest here, if i may.
Getting these drums out of the corner of the garage, that were at the bottom of a pile of crap that i had to move out of the way, to even get to them, to take the pictures, was a pain in the ***.
Now they are put back, in that pile, and i have no interest in digging them out again and dragging them around town, trying to find a shop that has a measuring tool getting them measured.
I don't know any mechanics in any shops, and don't know any shops that even have a brake lathe anymore.
Shops just remove and replace stuff these days.
The next time i want to ever handle these drums again in my lifetime is if somebody want's to buy them from me, then i will dig them out again.
If not, they stay where they are, and if i die next year, or whenever, the executor of my estate can clean out the pile and bring everything down the street to Schnitzers Steel, for scrap prices.
Guess i should have left them in the pile from the get go, and not even replied to the op's wanted ad.
For all that i know, somebody could be a buyer for these drums that's local to me, and have a measuring tool, to bring over, and then let him dig through the pile.
Stuff like that has happened to me before, with people seeing ads on Craigslist, or car related web sites.
You could have easily sent me a pm with your thoughts, without having to post your commentary in the op's ad.
But i do understand where your coming from.