The body plug kit is not correct for a 73. It wasn't correct for mine at least. I ended up reusing a couple of the smaller ones. I didn't have any pictures of where they went. I just had to use process of elimination.
There are more than you need of certain sizes and not enough of others. The orange ones for the shock absorbers are not the right color but they at least fit. As for a diagram, I have never found one. Just plug all the holes, cover them with carpet and trunk mat and call it good.
Craig