[stllookn]

There are two types one-part (stays flexible for a long time like the OEM stuff) and two-part (more expensive, epoxy type that takes a special applicator but is smooth and hard as a rock). The mess is getting the old stuff out and doing the seal job properly. This will require you to repaint the top of your cab and the drip rails. To do the job right you will have to take all of the old material out and clean the drip rail down to the bare metal. You can soften the old material with a propane torch and dig it out with a screw driver then use a high speed wire wheel or paint stipped to get the rest out. It is pain but it really should be done right to prevent further leaks and rust.