how would i go about back flushing from the thermastat

Spare is right, I was thinking the 488 4 cylinder. My bad guys, I'll take my beatings now.

thanks for the help guys i got the impeller done but the trick was to get the shift linkage hooked up right the first time i thought i had it was all reverse the second nothing the third lower unit wouldnt go on the last time an employee i call rusty bucket thought it would be easier to just go in from the transum side of the lower unit to line up the shift linkage