Hey Unicorn Z, 

I refabricated the under-structure with a MIG welder and 20 gauge steel. 

Then I used 3M body adhesive (product # 08115) to attach the top slam panel which I bought from Tabco.    I used the 3M product because:  1) It is stronger (read the research);  2) It prevents future rust (why let it rust again!?!);  3) It looks much better due to not having to drill holes; 4) It's easier.  Two buddies and I glued i on in  ~ 30 minutes. 

I used an electric spot welder that I bought t Harbor Freight to attached the panel to the supports in the middle - near the license plate area.  It worked out very sell.  Here are some pics...  They my be worth 1,000 words...  Lemme know your thoughts or if you have questions.

Now on to the spare tire well...:)  Jughead

Sorry - The pics and the text got jumbled up a bit.   

BTW: Here's where I am with the Spare Tire well. The donor well is ready to go in this weekend. I'm going to use the 3M Adhesive here too,

 

New spare tire cavity looks great. Couldn't tell from the photo, what did you use to coat the top of your replacement metal with before attaching the slam panel?

BTW:  I used a brake to get the lip for the weather seal, so it's all one piece.  Hope this helps... Jughead

The only thing between the panels is the adhesive.  Both metal surfaces have to be clean and bright.  The top of the replacement slam panel has auto body primer on it.  JH