Is it similar to the one fitted on an experimental Me262C-1a flown by Heinz
Bar (III./EJG 2 march 1945) depicted as profile #7 in Osprey's German Jet
Aces of WW2. ?

A rather fascinating view of the Walter HWK booster intended for the
Me-262 H.IV

http://www.walter-rockets.i12.com/ato/me262iv3.htm

Looks like its in farly good condition for its age.

Clearly, yes.
I wonder where this jewel rests.