This job isn’t a fun DYI. The hand you’ll us to pat yourself on the back for saving a few $$ with an after market tank will be the same hand slapping your forehead when you have to redo the job in a few years.
I know in spite of all you are reading, I will throw this out to you.
I have a brand new "German" brand tank in the box (With the paperwork) that I will let go at a very reasonable price, if you are interested.
PM me please, if so.
Go with OEM, I bought an aftermarket one and the port for the temp sensor was not fully cut and the sensor would not go in all the way. I had to pull it up again and ended up getting OEM after all.