109 Rear Shock Absorber Chassis Mounts

Any Advice would be so helpful. I have a 109 pickup I have been restoring I am almost finished the Chassis however the rear shock absorber mounts have rusted beyond safety. I have been trying to source a replacement set for the last few weeks with no luck. My next option is to fabricate them, but for the life of me I can not figure out the tube stock sizes used, I have written to a few chassis companies but no response. Any help would be most gratefully received.

This link, YRM might help ..