Vented G12T75 1960b cab opinions

[JLR]

Those vented 75's are the real deal. If you like 65's you'll love them. White oxidation could be leftover residual blow from touring.

 

[JLR]

They are good sounding, but very different from the vented versions. The vents sound like a high powered greenback, like the earlier brighter T3120 G12 65s can sound like a greenback. The white label/next version 75 after the vents have a much more noticeable mid scoop. But, they have WAY more mids than any T75 that would follow. My experience is the T75 kept getting more mid scooped as the years went on. In a gradual way.

Seems like the mid scoop increase late 80's on these 75's paralleled the metal genre surge of the same period. Seems like a valid correlation to me.

 

[Speeddemon]

and looks like it’s been wet. Flood damage?

Nah, it doesn't look like black mold. Besides, there are none of those brown/murky, wavey water-damage spots on the wood.
Most likely the back of the grille plate has been used as an underlayment for spray painting something else black on top of it.

A bit late to the game, but since I got my pair of vented T75's, after owning and playing non-vented old T75's for years, I preach even more now.
The non-vented ones, from '86 were already an insane improvement over the scooped, fizzy mess that these speakers became later.
The vented ones indeed sound very close to a G12-65 (the former material, Kaptop (T75) vs. fibreglass (G12-65) is the only difference IIRC) and the non-vented ones sound similar, but maybe a tad more muscular and punchy.
As anyone with good experience with the G12-65 can tell you, those speakers will sound smooth, to the point of 'dull/dark' if you don't give them enough volume; e.g. TV/dinner room conversation levels. Crank 'em and they come alive.
The old T75's are more or less the same, but they sound a bit more lively at lower volumes.