You're absolutely right, but getting at the backs of the guages requires taking the dash apart, starting at the bottom. Kind of a pain in the backside. I'm waiting until I have another reason to do in there and fix the guage lighting at the same time...
Man I know what you MEAN! The 80s dashs are complete PITAs to take apart. I once forgot to plug in my diff lock switch and realized when I wanted a locker it wouldn't go. I ended up ripping it apart in a safeway parking lot while the girlfriend got some supplies

I have to admit I got pretty quick at dismantling the dash after doing it a few times
/