It is a possibility, but it will take some work to confirm. According to my info my David would have been born about 1771. If the one listed in your census is correct he would have been abt. 69 in 1840.
I would have to look closely at the 1800-1830 Knox Co., TN census to see if a David was there and if he was not in 1840.
I believe the Smith family moved to TN in abt 1783 after the Revolution.
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