Hi Gord, what is it that you are trying to achieve by combining these objects together?

From what I can see I would recommend keeping them as separate objects, because there are numerous areas like this where 2 solids touch each just along a common edge:





That's similar to trying to combine 2 boxes like this that only touch at an edge:



But CAD programs are not designed to have a single solid object that is arranged in such a manner, something like that should be 2 separate objects rather than attempted to be combined into one single booleaned together piece.

- Michael