[38Chevy454]

Better with the angle iron and threaded rod to hold the batteries in place. The straps would eventually fail. Not so good having the batteries get loose.

Just curious why you did not just put the front main cross-piece on top of the frame flange? Instead of under it like you have? Seems you could have put one side in and then with it angled, slide the other side until it is 90 degrees. Could still have the clamps, but the clamps would not be in tension holding the weight, just keeping it from moving. I do think yours will work, but more critical on the bolts not coming loose. I have done enough drilling through metal from underneath, not much fun having hot chips rain down on you. The extra thick frame rails on our trucks make that even worse, so I can sympathize with not wanting to drill the flange.