Model 19-6 4"
I carried a Model 19-2 on the PD and I always wanted to buy another 19 to replace it. So far, I've ended up with three of 'em in the various barrel lengths.
I guess the point of the above story is that my current 4" 19 is actually a Model 19-6. It's the only one that I've seen, and it is quite the shooter. Here it is with its brothers.
Good luck. All the older Smiths are getting scarce and pricey in my neck of the woods. USBP Agent Bill Jordan was spot on about the 4" Model 19 when he said: "It's a peace officer's dream."