21CYP22 a.k.a. 6243?

[CT-100]

I recently acquired a CTC-7 in working condition. This particular receiver I was told, had never been serviced. After investigating the chassis though, there was evidence it had been worked on because two screws were missing from the shield underneath the chroma processing circuits and the retainer on the interlock had been removed. Nothing else appears to have been tampered with and the cabinet, aside from minor delamination in one area of the top, is quite nice.

What is unusual to me is that the Kinescope, while it has the split anode of a 21CYP22, it is not identified as such. Rather, on the base of the tube the numbers 6243 are printed along with "RCA SERVICE COMPANY".

My guess is this was a warrenty replacement. Any guridance from the community would be appreciated.

Regards.