I finished the removal and install today. I ended up using my Sawzall to bring the rivet down as close to the frame as possible and then the grinding was fairly quick. There was so little space to work with that it took a lot of taps with the hammer just because I couldn't get a good swing on it. I did end up putting a short bolt a little smaller in diameter than the rivet into a vise grip and hammered against that which gave me a little more swing on the hammer (compared to the drift). The two toward the back had to be done from underneath which was just more awkward and uncomfortable! Anyway, all set now.
Now my battery is more secure. I also did not have the top bracket thing to hold the battery down (I don't know how my uncle, the previous owner didn't lose a battery!), so now with the new tray I also have the top bracket that holds the batter down. HOWEVER, the battery posts touch on both sides the metal bracket. So, for now I quadruple wrapped the metal in thick electrical tape. When I got the truck, the battery was shot and the first thing I did was replace it. I had the truck only for a day or so and it seemed like the easiest thing to do was just get the same exact battery, so that is what I did. It is not the correct size, though - it is the right length and seemingly height, but the width or depth is much narrower than the tray.
So, maybe if I got the correct battery size, the posts wouldn't be so near the edge where the hold down bracket goes? Or, do they make plastic hold down brackets?
Looking at the auto parts store, the battery they list for my truck is a "Group Size 1-1J" but of course it is a 6 volt. When I feel like spending money again for a battery, I guess I'll start there and see what is available. The 6 volt pictured definitely has the posts further inward than they are on the battery I have now.
