Old Instruments with rubber rings?
 

Is it possible to mount old instruments with the rubber rings instead of the brackets that hold these?
The instruments are from a 69 912 and just want to use the rubber rings instead of the brackets.
Are the instruments the same diameter of newer ones?
The holes where the instruments are mounted are the same diameter in older pre70 and newer cars after 70?

Thanks

FWIW, I've bought a new (this was around 1998) clock in my '68 mounted with a rubber ring I purchased at the same time.

Didn't have any problem.

gauges are the same diameter, holes in dash are different size. am currently running around with electrical tape holding in my gauges until I figure this out.
look here.
http://forums.pelicanparts.com/porsche-911-technical-forum/392777-changing-early-gauges-slip-type.html?highlight=gauges

I did the exact swap on my 69 912. I used a rubber stretch type tape for repairing radiator hoses in an emergency (I think I got it a Pep Boys years ago). Anyway, one pass of the tape and the instrument fit snugly in the hole with the grommet. Couldn't detect a difference.

Same here, I have a late model tach to work with my crankfire ignition computer which was a hair smaller than the hole. I did two wraps of blue painters tape and it fits snuggly and perfectly.

Thanks for your answers.
Removing the old gauges with the brackets should be done only once, next time I will just pull them from the front of the dash, after doing what you recommend.