We dragged my wife's old Carter from the lake house and I have started work. The Tecky is out, and the Predator is on the work bench. I have a few questions that are pretty beginner level so please bear with me. 
The buggy currently runs a differential, which I am looking to replace with a live axle. It's well supported since it's got bearing "tubes" running across most of the axle. Can I make use of the tubes, just put keys where I need them?
I would like to set the cart up to move as efficiently as possible with a max weight of around 500 lbs (cart and two adult passengers). Where can I read in depth regarding kart gear ratios?
ETA: Found good reading here!
I come from the automotive world, so this is a new adventure.

The buggy currently runs a differential, which I am looking to replace with a live axle. It's well supported since it's got bearing "tubes" running across most of the axle. Can I make use of the tubes, just put keys where I need them?
I would like to set the cart up to move as efficiently as possible with a max weight of around 500 lbs (cart and two adult passengers). Where can I read in depth regarding kart gear ratios?
ETA: Found good reading here!
I come from the automotive world, so this is a new adventure.