The Master has single acting shocks (they only dampen in one direction). I had the same issue with my 38. I had the shocks rebuilt and it still happened. As it turns out it's not really a "wobble" as it feels at the steering wheel but rather an uncontrolled bounce of the wheel. I discovered that piece of info when I was driving the 38 home from the pinstriper's shop. I rolled through a pothole and the car started the "death wobble". The right front wheel was bouncing uncontrollably. The wife was following me home and told me it was the wheel bouncing. It had freshly rebuilt shocks but they couldn't stop the bounce. I used 39 Chevy tube shock mounts and replaced my lever action shocks with tube shocks. No more "death wobble".

I replaced 40 year old tires on my 1935 Standard and eliminated the death wobble. On my Model T Ford, I tightened the king pins so they squeezed the spindle a little bit and the death wobble went away. There can be several causes. Good luck finding your issue.

Mike

Tube shock mod kits are hard if not impossible to come by with many switching to IFS suspension

I don't believe simple bolt in kits are available but there are a lot of conversion kits that could probably be made to work with some fabrication.

Are the front and rear shackle and leaf spring bushings interchangeable 

thanks 

With my 38 Aus built 1/2 ton truck (sedans could be different) the shackle pins at the front of front springs (swinging shackle) and rear of rear springs (swinging shackle) are the same and rear of front (fixed shackle) and front of rear (fixed shackle) are the same.

Tony