Go to Lincoln's web site and look up the flux core you want to use. The web site will list the AWS specification and classification for the flux core with the brand name. Then look at D1.4 to see what electrode specification and classifications are permitted.

You don't have a copy of D1.4? Then how can you possibly meet the requirements of the code if you don't have a copy of the applicable code?

If you can't afford to purchase a copy of the relevant code, you can't afford to do the job.

Just my thoughts on the subject.

Al

steade1516
Attached is the table you need.
I agree with Al, having the COC in front of you is essential. You can easily find a PDF copy on line if you look. There are so many variables for you to consider, size of rebar, what type of connection, having an approved WPS etc. etc. None of which I could see the need to use a E91T8 on.