How to extend the diff pinion shaf:

On SCX10 gears, this would be easier: a longer shaft where the pinion fit...the pinion on scx10.2 has the shaft incorporated. So, I had the option of welding a shaft but would have to repeat that if I wanted to change the pinion. There was not space inside the torquetube to do something with a grub screw holding the 2 parts

So, the idea replaces the grub screw with a 2.5mm metal rod,hammered in the ends, like a rivet. This way, I can replace the pinion shaft and bearings