for a batter, sears sells HD closed battereies. They are expensive but they are Maint free and you dont have the boil out issues of corroded cables etc. A guy I know has a 17 model thor and he is already having battery issues with corrosion and its only about 6 mo old! Anyhow, go to Sandies on Miracle Mile for RV help. Sean and his mom are great people and if a cat lover they have this big ol black cat to pet also. I am pretty sure the dodge will be your weak link as many have had issues. go to a dodge forum and ask. My BIL put in a 4BT cummins to replace the one he had and it was in a class A type just to get rid of the overheat problems. There has been a story line of folks fixing up older MH's in the motorhome magazine. Often includes interior updates, new paint jobs etc take a look at them but they normally are $$ jobs which I dont think you are wanting at this point . You may be able to see them on the motorhome mag website?
As to leaks I am sure you will have a metal roof as at the time they didnt use as far as I know rubber on them. Seal the crimped areas and check there for leaks where it meets the sides. I had issues on my old slide in camper at such points. once you are ready to give it a try remember catalina park, pima copark on the west side by old tucson just for a close in getaway. When ready you can try picacho peak for an adventure down the road.
Also as a thought go to one of the hardware stores and get the spider bomb to clear it out if it has been out of use. Widows and other like to take up residence in closed spaces. I think I would just thrash all the rubber/foam stuff inside for GP's.
Have fun, I did when we got the old slide in back in 89, took it all over in the truck we had then.
