Days between dates with selected criteria

I need to calculate how many days are btween dates, however keep certain criteria in consideration.

See attached file for more info...

Your sample doesn't make much sense.
In it you ask:
"I need a formula that scans through Column D"
Scan for what?

"It should then take number in D2 "964" and scan down Column D
Find all the "964"'s and calulate days between dates, see above!"

There is only one occurrence of "964" in column D and that would be the one in D2.