I'll post about my Vito, serial number B22750, manufacture date of 1974.
Its not specifically labeled as a resonite, but it's not wood. It is marked only with "Vito" on the upper joint and bell, and matching serial numbers on both upper and lower joints. School inventory number WSD 74-132 is scratched into each piece, except the mouthpiece. The Vito mouthpiece pictured is my own, not the Encore one it came with. I can't find any info, other than the serial numbers put it at 1974. I've not found one picture like it, none. The knurled metal joint rings-bands make it distictive. Other forum members were sure it was wood, based on pictures, but it isn't, so maybe a prototype?
I think it plays very nicely and easily, I really like it a lot, and am not bothered that it isn't wood. I hope a lot of kids played it, and got a good start on clarinet. For a school instrument, with 74 scratched into it, telling me it was added to the fleet in 1974, and in my mind, verifying 1974 as a manufacture date, it's in fantastic condition, so I think it was appreciated by its players.
Lisa