I think those two are a few of the rarest:

A few years back somebody from the Def Leppard board mailed me that is one of the rarest most wanted items by the band ever! (I didnt even know that)
and

( signed by Phil)
and the (original) Savatage Sirens on Par Records (and signed by the band incl. Criss
besides the demos by Death Angel (Kill as one) and The Legacy (Demo: 1) and a couple others...
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PS: I have the
12" Maxi Single "Romeo" by Heavy Pettin on Polydor Records (advance single of the 3rd album, but the album was never released on that label! --- It came 5 years later on another indie label!) No idea if that is rare or not? anyone know?!?