[Boatanchors] 3B28 = 866a?

[Artmouton]

Looking at ebay for similar tubes and found one sale that indicates that the 
3B28 is drop in replacement for 866A.
Can anyone confirm that info.
73,
Art K5FNQ

Art Mouton

"[S]o long as the people do not care to exercise their freedom,
those who wish to tyrannize will do so; for tyrants are active
and ardent, and will devote themselves in the name of any number
of gods, religious and otherwise, to put shackles upon sleeping
men." --Voltaire