This question has been asked before and I believe the answer is basically no. Having said that, nothing is impossible,
but it's not a bolt on deal. There are a couple of threads on this subject: I'll try and hunt them down.
Edit: Look on the Logan sub-forum for a post from Woodzi titled "QC Gearbox". There's a link that takes you to
some information on that subject from Scott Logan.
At one time I considered adding a QCGB to my Logan 200. There is a way to do it, but you have to get just the right gear box to make it work, and then it requires a certain amount of retrofit work. Sorry that I don't remember the details, but it was about ten years ago now that I considered this.
Anyway, I ended up doing a project that required a custom thread - a double helix actually, and I was able to do it with change gears by calculating for a double start 1/2 TPI - in other words 1 thread every two inches. The lathe was not powered for this but used a Dremel tool mounted to the toolpost and I turned the chuck by hand, allowing the lathe to provide the gearing to guide the Dremel to cut the helix. I could have never done it without change gears. I decided at that point to just keep what I've got as changing the gears adds a little time to my projects, but it is only minutes per change. Not a big deal for me.