Very interesting Greco Helge.
Dowel tenons ended late in 1980 for EGF-850 and higher models.
I don't know how long they continued to be used on lower models.
Maybe Otto will have a better idea.
The medium tenon, closed O logo and oval model decal all suggest a pre 1982 neck.
All 1982 model necks from EG-450 to EG-1800 I've seen, have long tenons, open O logo and the smaller rectangular decals.
Pickups are production run #5 Maxons (date code probably reads right to left (#5,DD,MM,Y) so produced on March 2nd 1982.
If you can, could you post pickup resistance values at your guitar cord plug ? (at the end that plugs into your amp, rather than removing the control cover again) We may be able to tell you which pickups they are from resistance values, since there are no pickup model back stamps.
With volumes on 10 you will get both values on treble and rhythm switch positions and half the value in the center position. About 8 + 4 + 8 ohms.
Tone knob positions won't matter.
I would sure like to know it's production history, given it's pre 1982 neck, early 1982 pickups and late 1982 serial # ???
It is very likely the last Les Paul style Super Real produced.
If you ever decide to get it refretted, it might be worth just refretting the worn frets , if you can source a close fret match, and saving the Fret Edge binding rather than getting a total refret job, given the guitar's uniqueness.
Thanks for the pics.
Enjoy...