Im prompted to add yet another thread to the recent Centurion ones.
Not really a big Centurion fan per se, I picked my Black & Yellow Sport DLX up
from someone selling it for their Dad based on the great condition it was in.
What is wacky though, he swears it is a 1997 model and remembers buying
it well because they had to look in a few places to find a large frame(Tange)
to fit him. In researching it, I see Centurion stopped being Centurion
in 1990. The serial # is: F7 8245, the parts spec are different than
the Wright / Sheldon article because it has SIS Shimano stemmies and
a derailleur that just says 'Shimano Light Action' on it. As to be expected
it is a total pleasure to ride

Light Action SIS was produced from 1986-1988, so based on the serial number, this should be a 1987 or 1988 model. My database does contain another Sport DLX with an F7 serial number and Light Action SIS. If you can post a pic, I should be able to verify the year based on the paint and decal schemes.

I could see this bicycle hanging around in a shop for a few years, but a decade seems a bit much. The market for entry level road bicycles was drying up and being replaced by ATBs. If it is a very large frame, that would have made it even harder to sell.

Thanks very much Mr. Marshall !

Here is a bad/backwards MACiPhoto shot because this is all I had at my disposal
All dressed up for my 20mi-a-day commute through the wilds of West Palm

Yes, that's a 1987/1988 decal scheme. That two tone, tube based, paint scheme was definitely used in 1987. I don't have any known samples of 1988 Sport DLX to verify the paint but I know that the 1988 LeMans models used two-tone fade paint schemes. I suspect the the Sport DLX was probably the same, which would make your bicycle a 1987 model. To corroborate this, you could examine the component date codes using the info on the components page of the Vintage-Trek website. Don't forget that component model year manufacturing pre-dates the calendar year by about 3-4 months (i.e. components manufactured in Sepetember - December 1987 would actually be 1988 components). Good luck.

I'm guessing 1987. The Lemans had black/yellow around the same time, and the colors help the resale value even now. I think your components are mix/match due to necessity.