[Grammar] vacancy of an, position of (an)

[uktous]

Hi,

Question:
Which sentence is most commonly used?

Sentence1:
I have read your advertisement for the vacancy of an assistant manager.
Sentence2:
I have read your advertisement for the position of an assistant manager.
Sentence3:
I have read your advertisement for the position of assistant manager.

Thanks

 

[PlacidRan]

Sentence 2 is the best and is the most accurate one.