Dayton RS100-4 I have a set of these as desktop speakers paired with a small subwoofer and they are fantastic.
Tang Band W3-1364SA An amazing set of full range speakers. They're 3" so you'll need to make a bracket to make them fit correctly, but they are simply awesome. I have them running from 350hz and up in my dash location in my car, and I love them.
Fountek FR88EX Like the 1364sa's, an awesome full range speaker. A bit brighter due to the metal cone, but they also have a greater xmax, so they have greater output capabilities.
Tang Band W4-1052SD Nice 4" full range speakers that will be able to dig a little deeper than the 3" full range drivers at the expense of some top end. Still a great speaker that I wouldn't hesitate to run in a car environment.
The only downside to these full range speakers is that they will need some eq work and need to be installed on-axis to get the most out them. That doesn't mean they won't sound good off axis, but it's the top end that will suffer the most should you install them off axis. A nice aftermarket amplifier to give them some power wouldn't hurt, either, especially since you could use the crossover on the amp to block out the lower frequencies. But it's definitely not a necessity if you're just doing a drop in replacement.
Just to clarify, where will the speakers be installed? In the door by your feet? Or in the middle of the door? Either way, as drop in replacements, any of these speakers would be a great choice. If possible though, I'd build a crossover to block lower frequencies (a high pass of 80hz - 100hz would suffice) so that way, you can get a bit more out of the speakers. This is assuming you have a subwoofer to pick up the lower frequencies.
