I went one step furthur, the 3/4 ton and 1 ton diesel versions of my 1/2 ton truck have a second battery which is put in parallel with the first to get more power to start the big diesel engine. I found that the battery tray will bolt right up and bought one and put it in. I then bought a new battery for the truck and put the old one in that tray and put in a battery isolator to keep both charged but only allow one to discharge. So I can now jump start myself if needed. I've also added a secondary fuse block and a few power ports to that battery so things plugged won't run the main battery dead.