I have an early, dual pod dashboard so my approach may not work on the later single pod dashboards.
because of the aftermarket HVAC unit I installed in 2511 during the reassembly after the collision repairs, I had increased obstructions behind the tachometer which totally prevented the installation/use of the U-shaped mounting bracket.
I found that the round opening in each pod was a ....very.... close match to the outside diameter of the speedometer and odometer. Taking my soldering gun, I melted the pod opening edges in four areas, creating a melted plastic burr/bump at each location. the melted plastic provided four tight contact points that firmly hold both gauges in their intended positions; push them in and they are installed.
they are never going to fall out, can be pushed out from behind with a little effort, and no one will ever know the “correct” mounting brackets are not in use.
The factory mounting brackets for those two gauges have been a problem for owners since day one. I am not aware of anybody else who has used my approach but I am quite sure those that choose to follow my example will find it works out just fine.
Think outside the box, and think harder instead of working harder. 😁😁
Larry