1995 Ford F-150 Leaf SPRINGS

I have a 1995 F150 that has been a head ache. Ever since I bought it it's made a banging sound from the rear when you hit bumps. I thought maybe it was just the tailgate bouncing around. Anyway, the other day I'm looking and notice a large gap in my passenger side rear leaf, and there were only 3. Thought it was funny so I looked at the other side and low and behold, 4 leaves, no gap. So my question is this, would springs off of an f250 fit on my f150? Is there any modification or wold they just pop in? Any help you could give me would greatly appreciated.