Re: Sloppy Shifter Problem
Well, that's definitely not good.
I'm sure that this goes without saying now... But I'd make sure that you're all they way in park and setting the parking brake when you're on a hill.
I believe the chatter you're hearing is a safety feature. It's purpose is to keep the transmission from being shifted into park while the vehicle is in motion, or to keep the trans from being shifted to reverse while moving forward. Generally it makes a loud sort of "clicking" sound.
I'd start by removing any slack present in the shift linkage.
Also pull the column plastics and take a look at the column for any signs of damage or obvious causes of the slop (loose bolts, missing bolts, etc.).
Perhaps have an assistant shift the trans to all positions while watching the linkage at the transmission (obviously this should be done with the truck NOT running). When shifted to park, see if you can physically move the linkage any further towards the direction of engaging park.
It's kind of hokey, but you're basically just using your best judgment as to if it is fully engaging park or not.
Outside of adjusting the linkage, this is really just one of those issues where you have to inspect all the moving parts and rule them out one by one.
Don't guess, diagnose.