I have a 1961 made one. No hex bolt or fat slide. Mine is marked P38 actually. It was an interarms surplus import. Actually it was the first handgun I bought when I turned 21. I cannot shoot it anymore because like many early guns, the slide on mine cracked.

If you get one, make sure it has the hex bolt and the fatter slide. These are usually 70's era and later guns. The P38 was discontinued in the mid 90's. The hex bolt insert was a stop gap against the beating the relatively soft alloy frame took.

You can however put a later post war slide assembly on a WW2 era steel frame. Probably the most desirable guns that are post war are the very few steel frame guns Walther made commercially. But expect to pay over a grand for one of those rare ones.