LeTour Luxe vs. Super Letour should be easy to sort, based on the crank (triple vs. double), and the paint color.
It likely isn't a '74. The only lugged frames that Schwinn sold in '74 were the LeTour, Voyageur and Paramount.
The 74 LeTour wasn't made of chrome moly, the Voyageur that year had chrome lugs, and the Paramount... well those are obvious and easy to spot with chrome Nervex lugs.
Your '84 LeTour tubing decal would look like this:
Pay no attention to the Schwinn downtube decal on the photo above. I removed the original yellow and white graphic and replaced it with the decal from about '79.