Look at it this way,
I doubt that your tank and my tank are the same dimensions, well, 300 gal sized.
I did a ton of pre build stuff in Acad and SW and I spent numerous hours trying to find models of motors, trans, rearends etc.
I did not find anything close enough to trust and wasted tons of time.
So, I ended up modeling what I needed, and went from there.
Here is an example of what went into the mill and a snapshot of the tank.