I vote, not "fake", but not Vintage Sound.
I handled a lot of those parts back in the day. The vintage hi-power Motorola baseplate is sculptured, thicker on the ends; the photo is a flat-plate stamping. Vintage TO3 used a glass-like lead seal, not blue epoxy (would defeat the point).
> date code look plausible
And trivially faked.
> in 99 Motorola still made TO3 devices in Mexico
Then maybe it is genuine Motorola.
But as John says, the fat old Mesa 3055s were different animals from the epitaxial construction which replaced it all through the 1980s. Later 3055s are as exciting as a doublewide TIP42B.