Does anybody know if the steering column & box is differant on a 1970 ls6 chevelle compared to a regular chevelle? I was told that the steering shaft was larger on the LS6.

Not according to Chevelle restoration guide. 1970 was first year for variable ratio tho.

The rag joint is different on a big block versus a smallblock. That won't help you determine if it's an LS-6, since the L-34 and L-78 big blocks would have gotten the same joint.