Originally Posted by robocop10mm
I am not sure about the 3". Most "snub nose" 66's I have seen were 2 1/2". The 65 was available as a 3".
Was going to +1, but a quick Google found 3-inch Model 66's. I have never seen one before, and must assume they are fairly rare. Like RoboCop said, you will be able to find the 2.5 inch barrel much easier.
You should also be able to find quite a few Model 13 & 65 in 3-inch since this was a popular law enforcement carry gun for many years (the 13 was standard FBI issue back in the day).