Contrasting the previous two coins, this one was "big mac expensive", bought unattributed from our own @jdmern!
Gallic Empire
Tetricus II as Augustus
Mid/late 274?
Obv: ...TETRICUS PF AVG, beardless, radiate bust right
Rev: ... AVG, Pax(?) Standing, holding scepter
RIC 251?
Almost certainly barbarous

Tetricus II was the young son of the Gallic emperor Tetricus I, who ascended to the throne in 271. Probably owing to the precarious situation during the crumbling and final collapse of the Gallic domains, Tetricus II was raised to Caesar in 213 and held his first consulship in 274, presumably preparing him to rise to the rank of Augustus the following year. This never happened, as Tetricus I was defeated and surrendered to Aurelian in the fall of 274. Father and son were spared, and may have retired to obscurity--though the Historia Augusta claims the young Tetricus went on to become a senator in the reunified empire.
The only indication that the young Tetricus II may have served as Gallic emperor comes only from coins. Barbarous issues of Tetricus II are very scarce, but a few have all the hallmarks of an official coin. Such a move would have been prudent for a father about to go off to a war he was certain he would lose - a Caesar would almost certainly be murdered, but an Augustus may be able to rally the troops' loyalty and at least negotiate a fair surrender.
What really happened is anyone's guess. These were dark times for the Roman empire.
Please feel free to share if anyone has one similar!