The alternative crankcase I bought had an insignia/logo in the cast, some factory mark that indicates what factory made it.
I'm just saying that if you build a kit and you are not happy with some parts, it might be better else where.
With my present 365/72 kit I have found most parts in the kit to be really nice and preferred to the alternative parts I got - which are much more expensive.
With my 038/381 kit I made a couple years ago it was very specific exactly which parts was not up to the task as I use it for milling.
I go to something like DIY spareparts (or similar) that have parts diagrams and only distribute original parts directly from the vendor (Stihl/Husqvarna, etc).
And I look out the parts I want that dont hold water, and I also look at other parts that dont cost much. Some OEM Stihl parts for old saws are surprisingly affordable, freight cost may be high though.
So in my 038/381 kit back then it was; the clutch springs (lasted couple of hours) and the bar studs (made in too soft metal) and the chain adjuster (crap).
Also I needed to modify the oiler not to leak and to deliver enough oil, I did not spend the money on an OEM oil pump, but I would have if I did not successfully modify the one I had. And the crankshaft was not straight and true - bought +2 from Farmertec they where all the same. Then I got a different aftermarked one from a shop downunder and it was perfect. Had to wait two months and it ended up expensive - but it was worth it.
Offcourse the same kit now may be a totally different animal/production.
So the 038 holds up perfectly, it is now rock solid reliable and as I use it for milling it have really been tested to extent. Easiest saw I have to start.
Offcourse it is a "very" solid/rigid construction/design to begin with, but probably surpassed by the 365/72 for performance, and the 036/361 for weight.
The 046/460 will be my future milling saw though for sure. 4,4kw as original but with a 82,5ccm light ported cylinder - at the weight of a 65/70cc.
A modest calculation says 4.75kw, thats only surpassed by the 500i. Probably a disaster for global warming though...