503 Identification

I am a Newbee  to this forum and have high hopes of receiving god info and comments!

Knowing that the 503 is old in all regards, it is still a good, reliable engine.  I was fortunate to find a 503 purchased while the 503 was still in "good graces"  with ROTAX,  that is essentially is in off the shelf condition.  Never been run, never had fuel in it,  Carb ports still have plastic plugs, plug holes still have yellow plastic plugs, never been mounted.

Big question is "How old is it"?   The serial number on the engine nameplate  -  3987283. 

 If ROTAX Admin could put a manuf. date on it, that would be a big help.

next:  What is the shelf life for a new engine kept in storage?  Lastly,  Engine crank turns freely.  Only signs of deterioration are splits on the rubber sleeves on the spark plug leads connections to the coils (easily replaced). 

Should I do anything to the engine before using it, or  just run it as is?

Any input will be appreciated!

Tuneturkey

3987283 was produced 19-May-1992

( no other information is found in the factory database )

Engines need special periodic treatments to stay longer than a few months  in storage - you can check the manuals under "preservation"...

Thanks!