This would be an opinion question I suppose, but I suspect that my water pump is going bad on my Mach 1. I was looking at the Edelbrock High Flow Performance Victor Series Water Pump - Short vs the standard Ford Motorcraft PW646. There's about $120 difference between the two. I'm not planning to do any serious mods to my engine, so I'm thinking the PW646 will be sufficient. I will likely go ahead and change the thermostat while I've got the coolant drained. Speaking of coolant, any preferences with that? I live in South Alabama, almost at the Florida line, so that give you an idea of the climate I'm in. Over the last few weeks, it runs hot if I'm stuck in traffic and if I turn the heater on full blast, it goes down fairly quickly. I've also had a strange squeak while the engine runs and gets louder as the RPMs increase. My first thought for the noise was the tensioner pully, but I replaced that about two years ago. I'm thinking maybe the water pump bearing is trying to go out and isn't pumping right, but that's just a guess. It doesn't always squeak and the squeak doesn't seem to coordinate with the temp problem. Those noises are so difficult to pinpoint! You guys are awesome! Let me know you're thoughts! Thanks!