1972 - 1973'ish.
I don't have a Model 10, but if I had been there before you this would have been my post
Love the deep blue, are the grips original as well? Box or papers?
And.... Welcome aboard.
I recently picked up this 4" model 10-5 for $300. It's in like new condition with beautiful gloss blue.
Serial number D497xxx. I'm guessing it was made in the mid 70's, can anyone confirm the age?