Pat- I was wondering if 1/2" would be good enough. I think it's half on there now except it looks like it may taper from 5/8 to 1/2. if I use 5/8 I don't think I'll be able to find a shift knob to fit so I'm a little stumped on that.

That's a real nice offer ojh. I really think I may have been over engineering that base part and I think the simplified version (without welding) would work fine, but I will certainly give you a call if I can use your help.