I am curious to know about the degree of interchangeability in Waltham pocket watch parts. Is there any kind of “general rule”? For example, are parts from Waltham pocket watch movements of the same size (movement size) and within a certain range of years “generally” interchangeable? Is there any overlap with other movement sizes? By that I mean, are there any parts from different sized (Waltham) movements that are interchangeable?