The numbers you are referring to are mfg. codes. I'm guessing but it might be factory code (230) and date codes (5-52) may mean the tube was mfg'ed either on the 5th day or in the 5th month of 1952.
What are these tubes
I have an integrated amp with three tubes in the pre-amp. One of them is a Tung-Sol 6SL7GT made in the USA the other two are Raytheon. Underneath the Raytheon stamp are the numbers: 230, immendiately below them are the numbers 5-52. Does this tell me what kind of tube they are, or what I would need to replace them???