Made a bit of progress yesterday evening..
Had to do a bit of trimming and re-painting on the frame rails to fit this notch because they were slightly different.... but basically was an extremely simple process.
I put my son to work a little bit... Thought I'd snap a picture of him doing some work. He's turning into a pretty good wrench.
Heading out right now to finish up the rear frame section and install the rear body drop pieces. Will post progress later on tonight.