Then this is something that has been given to you, and not based on your own examination of the headstone.
As you give the text of the transcription it reads
[YE] G.T 79 YEARS OLD, DATE OF DEATH [1815.]
There are several curious things about this transcription:
a. The square brackets usually indicate "something that has been added" rather than something in the original.You see this when something is, for example, illegible, and the transcriber has added it as an indication of what he thinks he says, or what he thinks it should say.In this case the date in brackets is  and I'd have to interpret that as meaning the year was not visible when the tombstone was examined, and that this is someone's interpretation.It might be right, or it might not be right, but we don't know what it was based on.What we know is that it wasn't based on what could be seen on the stone.
b. The "[YE]" is curious.I don't know what that signifies, but was presumably something added by the transcriber.Again, I don't know what it means, or what it was based on.
c. The phrase "DATE OF DEATH" is very curious for a gravestone transcription.Usually the phrase used was simply "DIED".
d. "G.T"is also curious.Perhaps this is a footstone, not a headstone.Sometimes footstones are inscribed with a truncated description just to show you whose footstone it is. Sometimes the simpler text is used when a field stone is being used. There's no indication here that this was a fieldstone, and I['d be surprized if ANYTHING was visible by 1974 or so when it was transcribed.So I presume this is an engraved stone.In anycase, how do we know that this is the headstone or footstone for "George Teater"?(see comment below)
e. "79 Years Old" is also curious.usually the phrase is "Years of Age"
If this is indeed a footstone, and I think it is, then there is another possibility for interpreting this transcription. While the convention is to use square brackets to indicate the interpreted material, perhaps the transcriber did the opposite, and the only thing visible was "Ye" and "1815", with the rest added in.More likely, this is a mixture of matrials---I've still no idea what "Ye" signifies, but perhaps the stone original read "G.T died 1815"...in that case, it would parallel the adjacent stone "S.T died 1784".If so, then you could plausible argue that they were indeed the stones for "George Teeter" who is said to have died in 1815, and his first wife Sarah, thought to have died about 1794.Having the two adjacent stones together makes this particularly likely.
Critical, though, is the part that reads "79 years old".Coupling that and the death year of 1815 does indeed give a YOB of 1736.But this isn't the common way of writing an age on a gravestone.Usually it would be "79 years of age".Which makes one wonder if this also is an interpolation made by the transcriber.
This is a very useful bit of data, and certainly can be used to make a case that George Teater died in 1815 and was born in 1736.It is unfortunate that the transcription was given you in such an unusual manner, as it makes it difficult to interpret what it actually means.
Since Glen apparently is still among us, perhaps we could get some clarification of what the gravestone actually said?In particular, what was the significance of "Ye", and the square brackets?
My focus is strictly on the George Teater who settled in SW VA about 1772-1779.I look at him earlier and later than that in other areas because I'm interested in knowing where he came from and where he went. But the focus is on George in SW VA.
He's presumably the George Teater in Kentucky. The identity of "John George Dieter/Teater" is of interest to descendants of this person, because some have confused him with George Teater.For me, that issue is not of great importance;I personally think it unlikely.I'd be interested in seeing a vigorous proof that they are not the same person, but even an emphatic statement that they are not, does not prove that they are not.