As far as I can recall all three are not available in any single version of
Struts 1; if you have all three in an application you have too many libraries.
struts.jar - Struts framework, pre-1.3struts-core - Struts framework, 1.3+struts-legacy - Struts 1.2 support for a couple of Struts 1.1 things
(This is from memory; there might be some wrong versions.)