This RBG-97K DeLuxe oven was produced for many years, the first being 1966 and the last being 1972.

Some things changed during the production of this model. In 1968, the background and paint color of the clock/control panel glass changed a bit and filigree pattern on the oven doors changed too from vertical to horizontal motif. This one is a 1968 or later model but probably not from 1972 as the chrome finish wasn't supposed to be available that year (but it was available again in 1973-75). I think that 1972 is also the year where the lower oven went back to having no glass in it's door as it was before the 1966 "K" models were introduced. The 1973 models didn't see much changes from 1972, kept the glass in the top oven only but had woodgrain motif on it's controls and a dark background for the clock. 

These DeLuxe ranges had features that were previously found on TOL "Custom Imperial" models like the backlit control panel and dual ovens. During the first years of production, there were two Custom Imperial versions of this oven: The RBG-99K added a roast thermometer that the Deluxe lacked and the RBTG-99K had the "Tender-Matic" oven that was introduced in Flairs and some free-standing models the previous year.

The Tender-Matic feature was discontinued in 1968 and the Custom Imperial version with the roast thermometer was dropped after 1970.  The self-cleaning version of this oven (with no glass in it's doors) was introduced as a 1968 "N" model and was a Deluxe rather than a Custom Imperial probably because Frigidaire didn't install roast thermometers in self-cleaning ovens. I have one of these (see the attached picture). After 1973, the "Deluxe" was renamed "Imperial" but had no added features.