On occasion a carrier may use unique date values that you wish to convert.  

710621 = 6/21/71

If you need to convert this, you would add an additional column and create a calculated field.  The following formula makes the conversion and in this case assumes anyone born between '00 and '16' is born in 2000 or 2015 rather than 1900 and 1916.

It looks like this:  =IF(L2<=150000,DATE(2000+LEFT(L2,2),MID(L2,3,2),RIGHT(L2,2)),(DATE(1900+LEFT(L2,2),MID(L2,3,2),RIGHT(L2,2))))  

The 'L2' would vary based on the first field you are converting.  There is also a screen shot attached that you might find helpful.