Jim,

I have done the installation you describe. Use the smaller hole saw. Look in the
hardware store for a rasp that fits in the chuck of a drill (solid steel,
usually black, no sandpaper, drum shaped, about 1/2" in diameter and 1" long,
not including the piece that fits in the chuck). They come in various degrees of
coarseness. Get the finest one for the best control. Measure very carefully, and
be very sure of where you want this gauge. It's awfully hard to hide a 2" hole
in one's dashboard. Cut the hole with the holesaw (be sure you use the one for
metal, not the ones that are for installing doorlocks), then, very carefully and
with great control, enlarge the hole with the rasp. It might be a good idea to
check the backside of the dash before starting. Move all the wires, flamables,
etc. I have a '72, and I put the gauges in the space below the radio. Three of
them fit there very nicely. Looks almost factory. If you're not installing more
than one gauge right now, it might be a good idea to plan ahead for future
additions. 

Good luck, take your time, and work in a comfortable position. Measure twice,
cut once!

Andy McKinley
75112.2101@compuserve.com
'72 Westy, '64 Buick

"...the car itself was still full of bugs." -Heinz Nordhoff, 1948, rebuilding
the VW after the war.