Dash Guages Removal?

[BUXMAN66]

totally rewiring my'49 gmc,....and in the process of ripping out the old butchered-up '76 nova harness that the p.o. had ATTEMPTED to install.....i was trying to remove the old dash guages ( cluster of older stewart-warner..oil,fuel,voltage,temp., and the 5" auto-meter speedo.) it's hard to be able to see from underneath the dash,the mounting of the guages. around the outer diameter of the guage "pod" at 10,2,4,8 o'clock there is a small tab w/ a sheet metal screw, (pointy-end coming through the backside). how in the heck do you get to the mounting screws to be able to remove both 5" guages? can't see much from underneath,... so you gotta do your "seeing" by sense of touch,hunched up next to the dash sitting in the driver's seat.there's gotta be a way to release those sheet-metal screws...but how do you get to the head of 'em to back 'em out? are after-market guages attached to the bezel on the facing of dash? the one's i remember had a metal "hoop" that is bolted w/ 1/4x20's and the feet of the hoop go against the back-side of the panel that the guage is being attached to....