GMB is the only thing that has worked for me. I bought a Flow Kooler water pump for my 4.0 back in 2003ish. The pump was $120 and had an impeller with a metal plate attached. But I decided to get it because i enjoy upgrading things. The $25 GMB was purchased shortly thereafter to replace the broken water pump on my other jeep. The GMB was exactly the same as it when I first saw it. Flow Kooler only riveted a small plate onto the impeller to add $100. There is also a high performance GMB water pump but it always gets bad reviews saying it don’t fit because the impeller hits the block. Although I have not tried it, I imagine it is fitted with a plate that’s riveted to a regular pump in order to improve coolant flow. The Flow Kooler GMB came with both a thick and regular gasket. Instructions stated that if your impeller hits the block, you should space it more using either the thicker or both of the gaskets. There were no interference issues with mine so i used the normal thin gasket. GMB pumps are unique in that the area of the heater pipe that comes out from the pump is machined. They have an aluminum plate that’s filled with aluminum. I have seen a lot more 4.0/258/2.5 pumps like this. Grease. Grease.