RC Komatsu HM300-2 build Part 6

I'm more or less trying to build a Komatsu HM300-2 in 1/14 scale, I'm aiming for almost complete metal (mainly steel and aluminum ) but some parts may be temporarily or permanently out of plastic due to manufacturing limitations or ease of production
This part contains the bulk of welding the rear frame together and getting everything aligned. The piece at the end is part of the rear axle suspension.
This video contains welding and therefore flashing images, be warned.
My fleet:
Tamiya Mercedes-Benz Arocs 3363 Semi
Tamiya Mercedes-Benz Arocs 4151 Tipper Truck (custom bed)
Carson dump trailer 3 axles (2 axles currently)
Huina 583
Huina 580
DIY low loader
0:00 Welding the rear frame
9:40 Cutting the rear suspension piece