FGT 60C upgrade path

Hi, I have found an old FGT 60C running firmware version 5.2.4. Look like as per firmware upgrade patch page (https://support.fortinet.com/Download/FirmwareImages.aspx) that the latest version I can got to with that harware is 5.2.13. Is that correct? Can't it be upgrade to 5.6.3? 

I guess that as per the page, if I can't got further than 5.2.13, the upgrade path would be:  5.2.4 ==> 5.2.6 5.2.6 ==> 5.2.9 5.2.9 ==> 5.2.11 5.2.11 ==> 5.2.13

Thanx for you help!