I am for the 3rd time replacing my blower motor the first 2 were defective. My problem is with the alignment of the screw holes they don't match up so I can only put in one screw to hold up the motor which it will not do and there is obviously a big gap where I can't screw it into the housing. How in the heck do I fix this so I can have a correct as possible installation? 

Thanks 

They all should be the same housing.  Did you compare the old to new?  

I've replaced many and as long as the fan is clocked correctly all holes will line up.