Whenever a question like this comes up and no immediate answer is provided I like to use the data we have collected in the Registries and Production Number threads to provide an educated estimate.

In this case the Production numbers contained in the Production Number thread show that in 1959 there were 13,355 4 door 6 cyl. Strato Chiefs and in 1962 there were 15,520.

The 1961 Registry contains 29 full sized cars of which 6 are 4 door 6 cyl. Strato Chiefs. This represents 21%. The registry also indicates that at least 58,781 full sized Pontiacs were produced. Taking 21% of this gives us 12,340. This compares to known production in years around 1961 on the low side but provides us with a decent ball park representation that the representation of cars in the registry is reasonable.

An average of the three figures yields 13,780 we'd be safe in saying around 14,000 1961 4 door 6 cyl. Strato Chiefs were produced.

(Incidentally our family car in 1961 was a 1961 6 cyl. 2 door sedan Strato Chief - midnight blue)