Sounds like an after market modification.
Someone modified it.
50-350 usd
You need to find a gunsmith or firearms instructor
45 years old
50-1000 USD depending on specifics.
Mid 1960's.
100-450 USD
69-70
100-500 USD
Made in 1953. Model Numbers did not come into use unitl @ 1957. Sounds like you have a Chief Special Airweight. Later numbered as a Model 37.
Depending on condition of the gun and whether or not you have the box & accessories, $175-350
Sounds to me that you have a smith and Wesson mod-12.These fine .38 special revolvers are selling for 200-300 dollars depending on the overall condition of the gun.