Can I open the pump tower assembly to install the pump itself inside? Or do I have to replace the whole plastic assembly? Does the plastic come apart or is it all one piece?

 

You can install the electric fuel pump separately, as it's sold separately via RockAuto. The question becomes should you. With the amount of work required to drop the tank or raise the bed to access and install a new fuel pump, I wouldn't want to take a chance of having to perform that job twice, especially if the pump assembly is original to 1995. The sending unit for the gauge could die not long after replacing just the pump or the pump itself could be substandard and die prematurely as well. I just replaced a fuel pump on a '96 Dodge Dakota that I'm going to sell and I replaced the entire fuel pump module to ensure I would only have to do that job hopefully once.

Your call as to how you want to proceed...