1943 S Steel Penny FS-101?

Unfortunately, not a doubled die. The 4 in the date took a hit of some sort and flattened out the diagonal leg of the number. In addition, the S mint mark looks to have also taken a hit or was scratched and it is not in the correct position for any of the listed doubled dies for this year's steel cents. The doubled die varieties shown for this year show the mint mark to be tucked up and close to the date, between the 9 and 4, which is not the case with your Cent. Die markers such as the die crack you mentioned are excellent indicators but you need to look at all of the dynamics of the coin. Mint marks (Denver and San Fran), and their positioning in relation to the date, are a great start in determining if you may have a variety. Hope this helps.

Most will tell you -- Look for the variety FIRST, then the markers.