Creating a slot and closing of box section weldment

Hi, can anyone help me out, I am fairly new to Solidworks and I am a bit stuck with some weldments.

I am trying to model a swing arm from a motocross bike, but I am unable to figure out how to slot, and close up the box section to then weld it.

The dimensions of the box section are 40x20 (2mm section), the cut is 60mm long approx, and the dimension reduction is down to 33mm from 40 ready to be welded to the 30mm OD tube.

I've attached a picture of what I am trying to model.

Thanks,

Dave

SolidworksWeldments