Metric or inch fasteners

[ijpom]

I've done a modest amount of work on varied saws. The 80s/90s Craftsman/Poulan required inch size bolt replacement, while the modern electric SunJoe needed a metric nut in the drive system. This was found through trial and error.
Any way to tell what will be required by make, era or country of manufacture?
Should I assume most modern saws will be metric, because they are European or Asian manufacturer?

 

[Yukon Stihl]

i have worked on enough stuff with both metric and standard where i can tell by looking at it.
don't use impacts,don't force anything.

 

[46 Poulan]

Standard bolts will have dash marks on bolt head--6 marks= grade 8 American. Metric will have grade marks like 7.2--8.2..... Having a nut and bolt of each size you would see at your bench is very helpful in figuring out sizes and thread cuts-good standard and metric tap and die sets help also in ID of metric thread sizes--David--old Cat mechanic...

 

[HarleyT]

Most ipls tell you the size and pitch.