Dave, sorry to hear about the clearcoat problem, the new color sounds good, can't wait to see the pix. As for the threads, what you are referring to is the thread height. Threads are designed so that the main point of contact is in the pitch diameter area, the major and minor have to clear or you will get galling and parts will not mate. Threads have different classes wich controls manufacturing tolerances and amount of contact area. Class 3 is the most common in aerospace and yields higher strength than the lower classes, 1 and 2. A common problem I've seen in non-aerospace is the mixing of classes, i.e. class 3 bolt into a class 1 nut, a bad design. Imho, any shop that threads parts should be checking them. Just like there is a no-go gage for threads, there is also a go gage that is the minimum size for the specified class. The go gage must easily screw in, without force, the minimum thread depth needed. A shop that doesn't check their threads will have lousy quality and I wouldn't purchase from them.