You need to first ensure that the cab is mounted properly on the frame. For this to happen, you must have solid front cab supports (they take a beating over the years and are prone to rusting out), and as-new rubber in the rear cab shackles. You also need to set the gaps between the bottom of the front of the cab and the frame, and between the bottom of the rear of the cab and the frame. You can find these measurements in the Factory Shop Manual or at the online version of this manual.
Once this is complete, then the front clip is adjusted to fit the properly mounted cab.
The bed is the easiest to set level, but it would be hard to do if the cab is crooked.
Last edited by 52Carl; Mon Dec 09 2019 11:13 PM.