Your 880, being a 3 amp version, would date from 1976 to 1982.
An example of a Royal serial number, from 1970-76, would look something like this:
07J-N-12345
The "07J" would mean September 1970 (0 = year, 7 = decade of year, and J = month of September, month codes are given as letters A-M prior to 1985, skipping the letter I to avoid confusion with the number 1; after January 1985, the letter I was included to designate September, so that the month of December was now designated as L instead of M).
Then, after 1977 it looked like: 77A, where "77" is the year and "A" is the month code (the example is coded as January 1977). Around September 1978, the month code preceded the year, so we now see something like J78-A-12345 instead of 78J-A-12345.
As I said before, beginning January 1985, the nameplate changed and the text indicating the specifications was set in a digital font, and the letter "I" was included in the month code to designate September (hence: I85A012345 instead of J85A012345, which at that point meant October 1985 instead of September 1985, thus eliminating the need for the letter "M" as December).
The newer Royal to the right, the one you claim is a 996, appears to have the bag from a model 153 (it has a black top on it, indicating a shake-out bag). Both vacuums are turquoise in color as best as my eyes can see. I know the 992, 994 and 996 are all dark blue in color.
~Ben
And I LOVE that black+red DD! 
