BobS46, the decals from Chevsofthe40's are pressure sensitive adhesive, Did you remove the gauge face from the amp gauge? They are tough to remount unless you have the right rivets and setting tools.
The decals are good quality and go around the face really well, the small rivets that hold the face on are sometimes bothersome.
I cut around them and they worked fine (used a small x-acto knife). I didn't have to trim the decal other than that.