Will fit all 748, 916, 996 and probably lots of other Ducatis too. This is the exhaust valve upper rocker arm shaft (stamped A on the end). From a year 2000 748.
Ducati 748 916 valve cam rocker closing lifter arm left handed
Ducati 748, 916 & 996 4-valve V-Twins (1994-2001) Haynes Repair Manual
Ducati 748 916 996 S4 ST4 valve cam rocker pin cover cam belt side rear cyl
Ducati ST4 748 916 valve cam rocker closing lifter arm spring set x4
Ducati 748 916 996 S4 ST4 valve cam rocker pin cover open oil feed side rear cyl