Is there any simple way to convert text in Excel

19721221

to: 12-21-1972 ?

We are often sent birthdates in the top format and HAVE to have it
mm/dd/yyyy. I have been using the =LEFT function to split the text out,
rearrange, then =CONCATENATE to put it all together again. I'm having
problems though when dates are mixed with a month containing only one value.
Example: 1972314 / 3-14-1972

If anyone can figure this out ---they are a genius!