To cover most of the questions. YES the right ones have a small bushing that comes with it.
if you weigh 230 pounds or more you should get the Heavy Duty model.
If load of you and Passenger and gear weigh 460 pounds 50% of the time, you need the heavy duty.
The part number for the 412 for the America is: 412-4253C for the standard duty and 412-4252C for the Heavy Duty.
this is for the 12.5 stock length shocks, shorter ones are available.
I do have inside information on this and it is a bit accurate.
