Here is one more tip I can suggest! dont put the clear plastic back on until you are sure!, its a pain to put on and off, I leave it off until I am sure I have it set where Iwant to... If you have a USSPEDO overlay its some simple steps
Remove cluster from dash
Unplug cluster from wire (its a simple remove, funny and odd its my favorite wire connector in the truck its so simple

(thats sad ) )
Remove Clear cover
remove needles
Remove screws on the back (May not have to, I did for an 07)
Replace overlay
Replace screws
Plug cluster into car again (you will hear the needles reset to their home positions
Replace needles
Check accuracy
REplace clear plastic and mount into truck
Here is my cluster on my bed right after I switched the overlays out
http://www.ryangottlieb.com/gallery/photo.php?id=12
I also broke part of my clear plastic, well chipped off a decent size chunk (You cant see it, the grey bezel thing covers it) but I found its easiest to remove the clear plastic by using my teeth, just biting down on the little lock, I used the screwdriver or my hand and it broke, once I used my teethe, I never had a problem