I'm gonna guess yours is an XP as It's an 1989 model by the serial # If I recall correctly the 268XP model went out production around the same time Husky came out with the 272XP which was late 92 or 93. Most, but not all, 268s after that were non XP P&C saws.
Mahle is the maker of the XP top ends and Gilardoni the maker of the non XP top end versions. They also made the 268 Special during part of the later non XP time which had the Mahle top end.....these saws were much more rare than non XP Gilardoni model. I've used both top ends in ported and non ported versions......the Gilardoni P&Cs are very well made and no slouch but just can't produce the power of the Mahle XP cyls…....which are basically an advanced version of the 266XP cyl sporting much larger transfers and perhaps slightly better port timing #s to make better use of the enlarged transfer ports.