Bolt On Kit for any SB (Snap-Back) clock or thermometer.  You can tell if your gauge is Snap-Back by looking that the gauge's case back plate - if it is held in place by 4 small screws then you have a compatible gauge for this part.  We found some complete SB cases including stemmed case-backs. These full cases have no "guts" (empty shells) so all you need to do is remove the stem-back back, and use it to replace your stick-on back. 

The picture attached is "close to what you will get"!  You'll get a full (empty) gauge case and stem back, socket-head screws to mout the included mounting bar to the stem and a hex key.  The screw-driver you'll have to supply to remove the small screws.  Trust us - Super easy.