OK I will go along with this. Not that anybody I know would even consider such a thing including myself. Now is this 15 minutes for a home owner without a shop and no tools of course. Its sure has to be a lot faster with all the proper tools and a shop. I am out of the running on this one because it would take me more then 15 mins. to get the mower jacked up, get my tools out, and put things away after. I am just extra slow you know. I am sure a lot of home owners would also like buying a extra rear end just to store so they can change it back and forth as they need it. Now do you also need a extra pair of wheel and tires for this also? I find the average mower owner where I live don't want to change there own engine motor oil and filter much less change the rear end. I am also thinking the person who started this thread isn't thinking about this also, but was writing about a differential lock that came with the tractor .