I have a Bend Pak XPR12-CL lift which works great with my 10K E350 with penthouse. The lift has 2 minor drawbacks for my application. 1) When using the lift for a short wheel base vehicle like a Samurai or a Mini Cooper you need to position the vehicle forward of center to shove the front arms under it, then roll it back to get the rear arms to clear the rear tires. 2) The light weight Samurai and Mini lower verrrry slowly.
I bought the column extension kit and did not install it. All the kit achieves is to increase the vertical clearance below the crossbar. It does not change the height that it lifts the vehicle. I don't need it with my 2006 E350 with penthouse and roof rack. The kit consists of 2 column extensions, long cables and long hydraulic hoses. I will sell it cheap if any wants it. You will need to pick it up (San Diego area). PM me if interested.