I received my new motor and as I am figuring out how to install it, I see 3 screws. My question is, am I supposed to remove the bottom plate on the new motor to run those screws through and then re assemble the motor into the mounting flange, or are those there for a different engine and I have no need for them? This is a 1989 70hp mercury outboard. There were screws from my old motor there but when I took the four screws out of the old motor to access that plate the motor disassembled in my hands. I am very leery of trying to take this new motor apart and don't want it falling apart in my hands. Please help