I have something similar but different planned. I'm going to make a ring like this for the front case:



Then an adapter plate like you made for the rear case (only in 3/8 or 1/2" steel):



Only instead of having it welded on the end of the case, I'm going to use the plasma cutter to cut the shape of the "snout" of the married case into the adapter so it is a tight slip fit onto the snout.

Then I'll bend 4-5 pieces of 3/8" x 1.5" steel strap to connect the two... as shown is this really really poor MS Paint drawing. <img src="/forums/images/graemlins/scared.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" />