So, nothing matters here expect that all devices NOT EQUAL to DNS/GTM must have a version of big3d equal or newer. So, generally one would run big3d install script if a) you upgraded DNS/GTM first and now you need to run this on the LTM or b) want to protect against backward compatibility issues broken due to BIG-IP update. Please see the following: https://my.f5.com/manage/s/article/K25923322.
If you have upgraded the LTMs first (correct order), and now you are upgrading the DNS/GTM (to the same BIG-IP version) then correct, the version of big3d should be the same. You can check this a few ways: a) via /usr/sbin/big3d -v in advanced shell or b) iqdump. You can check both client and server BIG3D versions in the iQuery communications. See the following: https://my.f5.com/manage/s/article/K13703.