Beetle rear seats - what year model will fit mine?

I have a 74 Superbug L if it makes any difference and the rear seat base is missing in action!! Does anyone know what models had the same seat base so I can find a replacement? Saw a '66 rear seat online but not sure if it will be the same size. Real noob here sorry but love my old girl!

Something from a 68 or later should fit. Earlier models are slightly narrower.

Thanks for the info. I now know where to start looking! Cheers