I have created my own version of Ripsaw. 

You can find videos of Ripsaw on youtube and by clicking here.

My version contains 4 PF XL motors and has 2 speed gearbox which can be changed manually. 

There are no pictures of this gearbox, but pictures of a 2 speed automatic gearbox. Unfortunately, 

it is known that this gearbox was not strong enough and the small cog in the differential broke.
 
Write to me like if you have any questions at:

email: anders@systad.dk