'79/'80 side view mirrors question

I notice there are two types of side view mirrors that resemble the ones seen on the LRE's and other trucks. Some have four screws securing the base, and others only have two. Otherwise, they appear to be the same to me. Any other significant differences? I'm wondering if there is an issue with the two screw ones, like they tend to loosen or break off? Thank you.

The two screw ones are for 81 and newer trucks, sit over body line on them trucks, don't fit on 72-80 trucks

Ok, thank you very much!