I'd like to fire up the Cummins soon so it will re-energize me on this project. I cut a hole in the frame and fished the tank filler tube and vent through it. I'll reinforce that area of the frame with some plate when I can move it. Now I can finally fill the tank with diesel! I built an xxl battery box right near the starter. This should minimize the length of battery cables and be in a convenient location to access or jump them. I'll triangulate the mount back up to the frame eventually. Its fairly thick wall angle iron but it still flexed pretty good with the weight of the batteries.