Finished! Brutal 'Cuda
Figure this will help someone out, I installed a cheap Bosch (part#fst 7901 3 3/8") for a tach in the rally dash.
I apologize that I didn't document this better, I just got it done faster than I could take pics!
Ok,
once your dash is out start by taking the center out of the dash by unscrewing the screws that hold it in. Then remove the lense, I used a soldering iron to soften the plastic tabs that hold the 'blank' gauge lens in place.
(Ignore the gas gauge testing I was doing here...)