Factory for gears ? No Way, I tried with my new truck and was
told $1300 I said for a 2 wd, YEP.

If your near DFW I got a guy that will do it for $400 using motive
gears.

BTW my empty TT weighs 3400, WET and loaded I went to the
scales, 5100. I tow at any speed I want around here.