So i'm fairly new at things like this so forgive me if i'm just being an idiot. I have a 98 Dodge Ram 1500 that I replaced the rear drive shaft U joint's on. At the parts house they swore up and down that I need three U joints for it and went as far as to show me the diagram book. However getting underneath the truck and looking at it reveals only two U joints. One at the rear differential and one at the rear of the transmission. Then its just a big metal bar. The diagrams show a joint in the middle where it flexes. Any idea's on why this dodge has a seemingly incorrect drive shaft? Is it something that should be fixed? After replacing the joints its not vibrating or shifting roughly so I don't notice anything immediately wrong with it.

 

Quad Cab long bed trucks had a two-piece driveshaft. Shortbeds were one piece. If you have the longer truck, with a one piece shaft, someone changed it out.