I have a 89 Jimmy GMC full size with a 350 with a 160 therm. I was wandering if i replace my fan with an electric would it be cooler and what would be a good fan size for a 350 what cfm, 4 core outer oil and trans cooler. I was looking at one in summit that was 2100 cfm I have the upper fan shroud but no the lower. Is that enough cfm and if i put the electric fan on should i leave the should on? Thank for your oppinion.