Without calling Ruger's records dept, you don't There's no special prefix or such for the individual variations within a model line. Regardless of the model, all 10/22 use the same receiver for "blued" and "stainless" models. Remember, the receivers are all aluminum.
Can't. But, if you call the nice ladies at the Ruger service department they will tell you when the firearm was shipped and in what configuration, ie... 10/22T. Here is the # (General serial number information can be found by clicking here. For specific information regarding your serial number, please call our Records Department at 603-863-3300.)
They will also send you a letter stating such info if you would like, no charge.