OK, I have some confusion, and in fact my local shop does too (they are a first gen Camaro shop, but these parts shouldn't be any different)

Their first quote was for $470. Then they ask for $750. I think I found the confusion based on what I see on Summit. Any idea which is the correct output, and why it matters as long as the coupler is correct at each end?

Part 1120680020 has a 1 inch 48 spline output - $490
http://www.summitracing.com/parts/IDT-1120680020/

Part 1140680020 has a 3/4" 36 spline output - $780
http://www.summitracing.com/parts/IDT-1140680020/

EDIT: quick call to ididit solved the problem. The more expensive one is for column shift. I needed floor shift, so all is well.