I've notice the same thing. All my 034 AVS has been like the one you pointed out with 026 style starter cover and muffler cover with holes on the front. The other saw has starter cover that's wider but still plastic and side discharged muffler. Both are side chain adjuster. I did notice the one...
It could be a 034 super, my 034 jug would not fit the piston so it's the larger bore piston. The serial number starts at 1xx so it;s German and older. How do you tell difference between 034 and 036?
Few Stihls that is up for trade.
I have 2 036's. One older and one little newer. Both saws run well. I've not got around checking compression. the plastic are faded. One needs a longer pull cord.
Also have a complete and running MS440. The compression was 165psi. Small crack on the tank...
The washer is only need for the newer style oil pump, if you got the big circular oil pump like 024 behind the clutch, no need for the washer.
edit, from the picture below, you'll need a washer.
wow, that is the piston that I sent right? I didn't think it looked that bad in real life. That piston and my jug was making serious compression before. I think it was in 190-200 range with no gasket.
Let me know what you are going to with the piston. I'll take it back if you are going to...