Extracting numbers out of a string with alpha/number characters that are different lengths

I have a data set that has 3 types of data strings that are 10, 11, and 12 character lengths. I am needing to extract the 5th character (which is a number) followed by the following 3 or 4 numbers.
I can extract them from the 10 and 12 character lengths, no problem due to the numbers begin at the same position and end at the same position.

The problem is with the string that is 11 characters long.

The numbers start (from the left) at the 5th position, but some are 3 digits and some are 4 digits.
If you try from the right, the numbers will start from a different position due to a 1 and 2 digit number on the end. That number is not important for this issue.

Here are examples of the data:

NCAW1007AC8
NCAL390AC17

The string of numbers I am needing are:
1007
390

~frustrated with 'strings'
thanks!

no, it will always be a whole number of 1 or higher

You rock!

Thank you! Thank you!