The 4047 was built from 1974 to 1976 as a promotional model. Got this information from a listing Jeff Parker put together that was printed in the VCCC Newsletter several years ago.
Jeff
I recently bought and reconditioned a near perfect Hoover Convertible U4047 and absolutely love the "peach" color of this classic Hoover. I even found an NIB matching tool set that I still have not used. Hoover Y Carbon HEPA bags work great in it thanks to a tip from Fred Stachnik.
.
I figured that was it, but was hoping there was some magical way to do it without having to go through all that. It doesn't seem that difficult, though.