Here's a picture of the one I threw together to get this welder out of the back of the van. It pins to the heavy angles on the back of the bucket that the cylinder go to (put them there when I built it). There's a plate to spread the load to the top tube of the bucket.
Have since added a tension brace on top because it was flexing a bit more than I liked. Also need to plate the ends of the square tube on the bucket. It bent a bit transferring the loads.
BTW, the welder weighs something like 650# if I recall. Mounted to an AC D14.
FWIW. A.