Vern,I imagine the rag joint is/was there for reasons other than steering vibrations,it probably serves to allow a little flex between the cab and chassis too.
Maybe things are a bit too solid now.
I wouldn't think the steering box should move in any way,so like you say it might be prudent to clean things up and give things a really good check over.
Hopefully the solid mounting of the steering hasn't caused any stress cracking in the chassis.
Keep us posted of your findings.
