It's just an early '73. And not even that early. Production for the next model year started in August, so there was a couple months of '73 production before that one. Nothing all that odd about it.
My '72 Challenger was built 8/71. It did have some leftover '71 stuff, like the late '71 fuel tank and '71 dated gauges. But it was a standard dash so they look the same as the '72's.
Nice looking Challenger, btw. Lots more solid than mine turned out to be!
Would that have been a whole years leftover? They went to the 7 grand tach in 72, no? after looking at the pics again, that's a whole 70-71 cluster. The clock and odo resets are through the woodgrain, not through the speedo and tach lenses.