I found an old tv with 13 tubes in it made by sharp electronis. Im guessing the tv was made in the 70's, so are these tubes still useful for anything? I have some knowledge of tubes, but not much...

Member of the Morley PWB Owners Club.
Unlikely most of the tubes in tvs had little use in a guitar amp. And you really have no way to know if they are any good. In the old days there was a tester at the hardware store.
Even then, the tester wasn't very accurate. Metasonix uses TV tubes and all kinds of other wierd shit in pedals and stuff. They are known for that, plus the fact that all their stuff is blatantly over-priced and their advertising slogans include phrases such as, "Please, for the love of God, don't buy this!" and "This thing sounds terrible!".

Wiki it...
Get individual pictures of each any writing on the tube. Some of them may be useful, although they will probably not be compatible with many new amps.
I had an old ampeg that 2 of the tubes used were out of a tv or something else odd. Pretty much impossible to find I looked for a long time for those 2. I did find some but the cost was way to much 75 bucks or more for each. So before 1 of the tubes quit and the amp wouldnt work anymore I got rid of it. It also used oddball power tubes that werent to easy to get. And had a bad habit of picking up cb radios. Made money selling it so cant complain. So TS if you did find a use for the tubes it may not work long and might not be able to get a replacement tube from somewhere else.