Your rifle was made in 1977.
It's one of two models, here is how to determine which one is yours.
Measure your rifle barrel
Model CB Blue streak barrel is 19.5 inches.
Model CB9 Blue streak barrel is 19.38 inches 36.75 overall. It also has a Monte Carlo stock ( cheek rest).
The first Sheridan model C Silver Streak was called "The Sheridan" it was made from 1949 to 1990. After that it was called the C9 Silver Streak.
The serial number is on the left side of the loading port, in front of the model number. It may be under the black piece of rubber plastic.
I've looked at every reference book I have and can not find a model Sheridan 63-90 Blue Streak. The Blue Streak, As far as I know, is CB9 not 63-90. On the CB9 the serial number is usually on the left side of the barrel just forward of the loading chamber. You may have to move the black rubber piece of plastic clip that covers the barrel.
You cannot age a sheridan air rifle with no serial number. ----------------------------------- New Answer------------------ The above answer is not entirely correct. Sheridan rifles did not carry serial numbers before 1972. So if yours has no number it was made before 1972. Also if you can find the model number, then that can identify the date range that model was made.
Sheridan C silver streak in good condition would be worth between $125 -$160 USD
By the serial number and the model number. See the link below.
What is the age of a Sheridan c series 5mm 20cal rifle serial number 370862
It depends on the model, but usually it is right on the barrel or the receiver. If it is really old it may not have a serial number. For a time Benjamin and Sheridan did not serialise their rifles.
It all depends on age, use, and condition of the rifle. Is it in Poor, Fair, Good, Very good or Excellent condition. Sheridan made 4 different model C series. The C Silver Streak, C9 Silver Streak, CB9 Blue Streak, and C9BP. Which one are you asking about?
I believe you are asking about a Sheridan .20 cal Silver Streak or Blue Streak. This model is still in production today. A brief history. Sheridan, Benjamin and Crosman were all separate companies at one time. In the 1990's Benjamin bought out Sheridan but continued to market the Sheridan .20mm air rifle. Benjamin made an Identical model called 932 (.22 cal) and model 937 (.177 cal). The .20 cal stayed with the Sheridan. Later Crosman bought out Benjamin, but has continued to make the Sheridan and Benjamin series. If you still want an old one then I suggest you try "Gunsamerica" online they occasionally get one, or Gunbrokers online. See the link below.
It's very hard to date a Sheridan rifle. Let me explain. Sheridan started in 1945 and produced single shot air rifles. In 1977 Benjamin air rifle bought Sheridan and continued the line. In 1992 Crosman bought Benjamin. And again kept both names in manufacture. They decided to use Sheridan on the 20 caliber rifles and Benjamin on the .177 and .22 caliber rifles and air guns. At one point you could find both names on the rifles. In 1995 they came out with the C9 Silver streak model which later added the CB9 Blue streak model. there have been 4 different variations of the Blue streak. It's still made today. Crosman made some changes with their serial numbering system and I can't pinpoint your date of manufacture. See the links below
It's usually on the left side of the loading chamber or barrel.