First started at the bottom and installed the DKLM metal road wheels, suspension arms, return rollers, idler and sprocket (well only done one side so far)
I bought an extra set of the 550 motor 4:1 gearboxes last years along with the Leo2 complete metal hull. Which was before the Challenger 2 was launched, but since the Chally is narrower in the tub the 550 motors will not fit. So Plan B replace them with brushless motors.
Installation is simple, remove the original gearboxes and where the screwed down by 3 screws drill then through with a 3mm drill, then attached with 3mm bolts/screws from below.
But brushless motors need brushless ESC and special electronics, but I have IBU3 which can control external ESC. So a quick play around with internal placing of items to see what fits where.
All looking good although doesn’t look like room for a smoke unit.