I too, have a S&W 66 w/2.5" barrel. It's a -2 model, and I have the OEM box, papers and tools that came with it.
It has a red ramp front sight and a white outline rear sight. It only has about 50 rds. thru it since new. It is in flaw-less condition.
I wouldn't let it go for anything less than $800.00
Just for the record, the older S&W's always command a better (higher) price than the new ones do.