calculate vehicle number plates sequence
 

Hi,
Here is an interesting problem I wanted to try and solve with excel.
I have a series of number plates ( OAS 093 through to PWD 743 ).
These are the number plates that appeared on vehicles during 1972. I don't need to be too accurate, but I would like to know te series of number plates that would have been released in July ( half way through the sequence ). I am making a huge assumption that number plates were given out evening each month ( I'm not worried about the assumption ).
Firstly, is this an excel possible problem and secondly I'm getting lost trying to write a formular to calculate this.

result, possibly to look like:

1972

Jan OAS093
OAS094
etc...

Feb OA????


any help would be greatly appreciated,
thanks ...