It's an acrylic shell, all of the hardware on the tub visible in the pic were commonly used in the 80's ( jet's, high mounted suction fitting, air control knob, air button ) and the air line holes on the seat area inside also date the shell to the 80's
It doesn't matter what it is, I can make a hot tub out of a 5 gallon bucket, what matters is whether or not it has any restorative potential that would justify the costs necessary to make it operational again, that answer is NO.
The structural integrity of the acrylic sheet would automatically banish it to the reject pile, not to mention the current state of the mechanical bond between the gelcoat and acrylic sheet and any issues with the air channel, all were problematic known warranty issues with this manufacturing process.
Don't put lipstick on a pig.
