Help dating these 2 Smiths

[buttsm]

I have 2 recently aqquired Smiths I am trying to date:
1. Model 58 serial # N179***
2. Model 66-1 serial # 74K67**
The 66 barely has a turn line, the 58 wasn't shot much but carried a lot

Thanks

 

[JP@AK]

Model 58 serial # N179***

Theoretically from 1973.

Model 66-1 serial # 74K67**

The 74K numbers were used in 1981.

Note: That is two years after S&W used 75K through 77K; and one year after they used 78K and 79K. A perfect illustration of how serial numbers were neither used nor shipped in order.