.
Hmmm... That serial number would indicate a frame MANUFACTURE
date of 1985 (the 5 after the initial N) and the second
half of June (the fortnight indicator L). So your frame
was made a year or two before the aqua\silver frame that
sold on eBay and that COULD mean your Elite's specs might
be closer to those of the Elite 12 RS in the 1984 catalog
at
www.sheldonbrown.com/centurion. Not sure of this.
.
I say COULD because some frames made as early in the year
as June\July are the following year's MODEL. For example,
my 1988 Centurion Ironman Dave Scott Expert was MADE in the
first half of July 1987 but it is definitely a 1988 MODEL.
The color scheme, graphics and TIG-welded fork crown confirm
it beyond doubt.
.
You might try to get hold of some old Bicycling Magazines
from 1985 and check for ads\articles promoting\discussing
the Centurion Elite RS of that year. They might include information on
frame materials and components you may be able to match up
with your Elite. Without knowing the original color scheme
and color combination, however, it might be hard to tell
for sure if it is a 1986 MODEL but components may give a
clue.
.
Confusing isn't it.
.