Im stumped... what is this thing??

[AnotherNewguy]

First off..the tank in the pic has a stamp on it that says faber, this is fairly new for their tanks, and not present on their scubapro tanks. also they stopped making tanks for scubapro at least 10years ago and if you will examine the pics i posted this tank looks brand new. also i VIP, O2 clean, and fill tanks for a living so im pretty sure i have a good idea of how the valve works.
...and, if i had the rest of the markings then i wouldnt need to post on here now would i???
faber pust slashes in their serial #'s that make them look like dates if you dont know what ur looking for so i think thats why he thinks the original hydro is 04/1984 when in fact it is part of the serial#

Can anyone tell from the pics if its a 7.25 or an 8 inch diameter?

I'm not trying to be a jerk but you say you fill and service tanks for a living but you can't tell if it's 7.25 or 8"?