034
I believe you will find this to be a bolt on. The only difference being a larger bore. I will check on the stroke, but I think the previous post is correct. In some of the replacement manufacturer's listings, you can usually find the largest bore is being sold as it will fit on the regular models. The only saw that was stroked differently in the Stihl line was the 024 super. Same size piston as an 024, longer stroke. This has now become the 026
028 replacement will be 028 super, 034=036, 038=super or magnum, 045=056super(magnum has a larger bolt pattern).