Tektronix 2A63 Instrument Reference Book page 12

CATALOG
CHANGE IN PLUG-IN TYPE DESIGNATION
Sometime in the next few months Type 63 will be-
come Type 2A63.
The primary reason for the change is to make the
type-designations consistent with the new system.
TEK 2A63 IRB
1-25-64
SPR-131 8-15-62
Examples; 3S76, 3T77, 3A74, 3Al, 3Bl, 3B3.
Except for the 2B67, there will be no electrical dif-
ferences. Grey knobs instead of black knobs will
be a distinguishing mechanical difference on the
2A63.