Dining table height is generally plus or minus 29 inches. This is an Eames Contract Base table, first introduced in 1958, with the introduction of the Eames Aluminum Group and made pretty much continuously since 1958.
The Eames Contract Base table of 1978 was made the same way as the Eames contract base table of 1958. There was a period of time when these came with real wood veneer tops, but those have been made available again, so that's not necessarily the best clue.
Best way to date is to find out on which date the original owner bought it. Sometimes you can get an approximate idea of age by a tag or label, but tags and labels often fall off, and people sometimes substitute tags and labels.
If you need any help, please contact us at – info@designaddict.com