I stand corrected, looks like that bar has definitely gotten hot at some point. I run .325 .063 74DL Stihl bar and chain on mine and it cuts well.The drivers are beat/worn badly from that worn out rim drive, a new 60 drive link chain would fit and tension properly. That bar fits all the Stihl magnesium crankcase saws from the 024 up to the 066 , MS260 TO MS 660.
Thats 18 inch.