Very early build '69's got the chrome one as they ran out the stock, after that it is wood grain.

You may see cars like the Charger 500 with the chrome, this is because they were among the first units off the line for 69.

'69 Hemi Charger 500, ‘70 U code Challenger R/T
(These and a bunch others at www.dkowal426.com)

P.J. O'Rouke: "The old car ran perfectly, right up until it didn't."