Dyna Glide ModelsSuper Glide, Super Glide Sport, Super Glide Custom, Dyna Glide Convertible, Super Glide T-Sport, Dyna Glide Police, Dyna Switchback, Low Rider, Street Bob, Fat Bob and Wide Glide.
Adjusting the rear shock pre-load is for additional weight. It tends to make the ride a bit smoother with a rider on the back and helps to keep your shocks from bottoming out on bumps. The tool that Harley sells works great, if you use anything else to take the chance of scratching up the shocks, which may not be worth saving a couple of bucks on a tool.
I would stay away fromt the HD spanner wrench its garbage. Get and adjustable spanner from Sears. It might cost a little more, but it's well worth the additonal cost. And it is easier to use.
I use a rubber strap with a handle on it , like the oil filter wrench you use and I put it at the base of the shock and tighten the rubber strap on to the lower part of the shock and turn it . It worked great for me . P.S My bike came shock on number 3 and rode it for about 1000 miles that way . Then ajusted them to number 2 and I like it better this way . I am 6' 1" 240 lbs it did not ride as hard .