It's still crazy, regardless of whether you got the tranny free or low cost.
It's similar to having a machine with a mobo/cpu/video setup you like with an hdd. You decide you want an ssd so you buy a machine with a mobo/cpu/video you don't like but that has an ssd. You then swap the mobo/cpu/video into the new machine to use with the ssd. It makes much more sense to simply change the hdd to an ssd.
Originally Posted by Smart_Guy
I now bigger tires hurt low speed acceleration do to the extra needed force to rotate it but give higher top speed. It also gives wrong reading on the speedo.
It doesn't matter where you change the ratio, the result is the same. Changing the tires or the rear end effects the ratio of how many times the wheels turn vs how many times the driveshaft rotates. The speedo error is also introduced in either case and the speedo should be recalibrated when either the read end or tire sizes are changed.