Wow! Ouch, all at the same time.
If it is 0.045 inch diameter it is most likely gas shielded flux cored wire. If it is carbon steel, it is most likely E71T-1 and can be used with CO2.
The best you can do is qualify a procedure to establish the welding parameters, perform the bend test and tensile tests, and then send out an all-weld metal sample to determine the deposited chemistry.
The problem is, you don't even know whether the electrode is from the same manufacturer or the same lot. So, you still cannot confirm it is all the same.
I hope you have plenty of noncode work to use it on.
Al