In a review I have determined of a SAR that should have been filed no later than April, 2006 but was not reported to me. My question should I go ahead and file the SAR even though it is beyond the reporting deadline.

I believe that I should go ahead and file. What are your opinions?

I think you should if you are still convinced that the transaction was suspicious.
Provide an explanation for the delay in reporting - the steps that have been taken to prevent this from happening in the future and ensure that your file is documented.