I owned a Model 42 Airweight Centennial back in the day. It was my BUG when I carried a badge for a living.
The re-introduced Model 40 is identical with the original Centennials with one exception. The originals had a pre-drilled hole thru the grip frame and grip safety, and came with a factory supplied pin so you could lock out the grip safety. Just depress the safety, line up the holes, insert the pin, and voila! the grip safety is deactivated.
Any gunsmith could drill the holes and make a pin so you could do the same thing to the new model.
The new Model 40 is all steel, and IMO is strictly a holster gun & a bit heavy for pocket carry.
Yes, the new Model 40 Centennial is a classic. +P rated and no internal lock!
Now if only S&W would re-introduce the Airweight Model 42...