For what it's worth if you intend to do a lot of manual shifting (like I do) then a ratchet shifter is a great investment.

It lets you ratchet down and up so you never go further than you intend and reverse and park are locked out completely.

With my stock Chevelle shifter I managed to accidentally go from 2nd to reverse a couple times...that's not a fun experience.

I manual shift my transmission as of a few years ago. Reason being is a guy I worked with had a SN95 Cobra that had some good work done to it. I at the time drove my 99 SS everyday. We always played around with each other but never actually had any good pulls. We went cruisin one night and we did have the oppurtunity. First two runs I ran him with my shifter in O/D and just going WOT. I wasn't walking on him like I thought I would. The last two pulls we did I ran him with my shifter in 2nd gear and pulled him on him quite a bit more. From that point on anytime I run someone I run the gears with the shifter myself.

I have an upgraded Level VI in my truck and always put it in 3rd for 1/4 runs. I can feel the difference between keeping it in 3rd or 4th.

RPM Transmission makes a great 4L60e, and it has been flawless for over 10K miles now.