gojunior:
You have a .38 Miltary & Police revolver manufactured between 1948 & 1951. In 1957 the .38 Miltary & Police became the model 10 and with some design changes continues in production today. The finish would be nickel, unless it was redone in recent years, in which case it could be hard chrome. Stainless steel guns didn't appear for another decade.
The numbers under the cylinder yoke are assembly numbers, used to track parts in the factory. They are irrelevant once the gun is completed. Only the serial number has any legal meaning and is the only number that is tracked.
Value is not high, as several million Military & Police revolvers were manufactured. In very good to excellent condition it may be worth $300 to $350.
Because there have been several design changes over the years not all modern parts will fit. If you ever need spare parts try
www.gunpartscorp.com Numrich Arms are the junkyard/wreckers for the gun industry.
Your gun should be safe to shoot with any standard pressure or PlusP rated .38 special ammunition. Avoid any ammunition marked +P+ as there is no industry pressure standard for such rounds and you may be looking at unsafe pressures.
There is a how to check out a revolver thread stickied at the top of this sub forum. If your gun passes the tests then it will be safe to shoot.
Welcome to the forum, I hope you enjoy the experience.