I think I mentioned this earlier but just to be sure
--- 'do not' use GL5 gear oil in your MT.
That's the stuff sold in all the Kragen and Auto zone mass market type stores. They'll tell you it's ok to use. It's not.
Use the synthetic Redline MT 1 or Amsoil brand equivilant. NAPA carries it. You can also use GL4 80-90wt and a 1/2 once of friction modifier ( can't think of the brand, senior moment) good stuff just thicker, might make 1-2 shift slow.
I've had 2 batteries in mine for 5 years or so. Ones a Dual starting the other deep cycle . (I'm too cheap to buy an isolator or a $40 selonoid type switch). I have a 6 gauge wire running from the starting battery to the deep cycle, and the deep cycle grounded next to that battery. If I'm gonna run (my dog fan) an accessory long enough to run a battery down I just disconnect the cable between the batteries. I like the solinoid isolator switch idea that was covered on here at length on different setups and opinions on how to. I can't find it to link it , but it's on here.

edit,,Stalube brand