[Amps] 3CPX vs 3CX tubes

[Gudguyham at aol.com]

Hi, Does anyone know with any certainty the difference between a 3CPX and a  
3CX tube?  Checking the Eimac data in reference to a 3CPX800A7 vs a  3CX800A7 
it shows that a 3CX800A7 and a 3CPX800A7 both can be used in linear  
operation.  As far as the 3CPX1500A7 vs the 3CX1500A7 it does NOT show  usage of the 
3CPX in linear operation, therefore, could the 3CPX1500A7 be  substituted  into 
an AL-1500 or similar amp without any caveats?  Some  time ago the question 
arouse here and Mr. Measures said it could be  substituted  with no real 
problem.  Was wondering if the rest of the  knowledgeable concur with him?  What say? 
 73 Lou  W1QJ