Thanks for the advice. A pulled battery cable and pictures are noted. For whatever it is worth, the truck is still on a 6 volt system.
I have put this project off as long as I could; I am not looking forward to working in the cramped space. This is one of those projects where I feel like I have to get myself in the right frame of mind to tackle. Finding a comfortable work position for a guy my size, wearing bifocals, having had back surgery (1999), will be a challenge.