While Stihl had made numerous changes to the gearboxes through the years, they have kept the threads on the stub shaft largely the same.
The most popular and standard head that comes on most straight shaft Stihl trimmers is the AutoCut 25-2 which is Part Number 4002 710 2108.
With the above in mind and knowing which Stihl Models use the 25-2 line head I did a "part search" on the nut that is used to hold the metal blades on the same stub shafts. That nut by the way is Part Number 4126 642...
Stihl Gearbox Threads
The most popular and standard head that comes on most straight shaft Stihl trimmers is the AutoCut 25-2 which is Part Number 4002 710 2108.
With the above in mind and knowing which Stihl Models use the 25-2 line head I did a "part search" on the nut that is used to hold the metal blades on the same stub shafts. That nut by the way is Part Number 4126 642...
Stihl Gearbox Threads