20J and 20K

[saxophyte]

How do you tell the difference between a 20j and 20k valve cap if you have neither instrument to try them on.

[bloke]

all the same parts for both.

Guide pins for valves #'s 1, 2, and 3 are propriety, but still the same for both the tuba and the sousaphone.

Of course, the pistons are NOT the same.

[saxophyte]

Yes looking at the catalog first would help
Thank You