Acquired grampas '70 somethin L245DT

We called him pappy and miss him a lot. Pretty sure he bought it brand new and it still runs but I'm trying to restore it to at least original operating conditions. Maybe when I have the time and $ I could make it look new as well. Current issues include mystery wires and how to know if electrical components are correctly working. On the bright side it cranked when I tried to start it so there is hope***128512;

Am I safe to assume the 3 wire bundles zip tied under engine and to back of roll cage are for the lights? Also the operator manual I found online has 2 wire diagrams but I'm not seeing any differences. Thankfully theres only about 50 individual wires that should be there from the factory compared to the modern stuff I'm used to with a thousand or more. Definitely appreciate your response though. Thanks...
It was dropped off to me after my cousin tried to add after market lights then couldn't figure out some of the wires were literally disintegrating.