[Boatanchors] Tube Recommendations???

[Michael D. Harmon]

I have a couple of surplus ART-13A transmitters, and I'd like to get a 
spare set of 811 modulator tubes.  Someone told me some time ago that I 
should use the original 811 tubes rather than 811A's. Is there any truth 
to that?  The 811A's are built heavier than the 811's, and they are 
certainly easier to find.  Is there any reason to try to find a set of 
good 811's or will the 811A's work OK in the transmitter? Are there some 
characteristics that make one better than the other?

Thanks for the advice!

Mike Harmon, WB0LDJ