What kind of bushings should I relpace my old ones with?? The springs are in a 2003 HD Dodge Ram 4x4.

 

Urethane bushings will ride a bit firmer as they flex less than rubber. They will also squeak to let you know when it's time to grease them.
Rubber will ride softer, and if your springs are as stiff as the ones on my '03 were, that's what I would stick with.
If you do decide to go with urethane, make sure you lube them with a lithium grease. Petroleum grease will break them down and make them come apart much quicker.
Hope that helps.