[rotorwrench]

Welding found on the frame could have been done for a number of reasons. I've seen quite a few that were welded to repair cracks. I've also seen fittings and cross members welded due to loose or missing rivets and some with elongated holes. You never know what you'll find. Shortening is mostly done to make doodle bugs but they are usually too short to use for anything else.

The Les Andrew's Mechanics Handbook Volume I has a good rundown on frame holes with bolt sizes for the different model A applications on pages 1-25 through 1-32. The book is short on photos since it mostly uses illustrations but it has a lot of good text information.