Motorcycle Repair: changing shifter shaft, splined shaft, head bolt

Question
I have a 1970 Electra Glide.   It has an unsplined shifter shaft.  Myshift lever slips, no matter how much I tighten it.  

Can I replace it with a splined shaft even though I see in parts catalogues that the splined version is for years '74 - '84?

Answer
I dont think the splined shaft will work with your bike, but here is what I have done in the past. Drill a small hole in the shifter shaft then tap it. Drill a slightly larger hole in the shifter and then install a allen head bolt with some locktight.
Good luck and happy riding
Mike