Help data codes on tube

Found following data codes on e188cc/7308 tube:


7 4 E

It's a steel pin with cross ridges on top of the glass. Probably Amperex or Philips related. Bur not sure they would be 7308.

Could someone with data codes information please check it out for me.
GA is tube type ECC88. C is the change code.

7 is Philips, Endhoven Radio valve lab. Physics group. Hitachi, Japan.

4 is 1950, E is May.

John C.
Thanks, much appreciated!