The same size cab will fit the frame from 73 through 93. Somewhere in the early 80s, the body lines moved on the cab, and Dodge modified the door striker location and set up. Between the late 70s and early 80s, Dodge went from the birdbath hood to the flat hood, so along with the hood, you also needed to change the piece under the wipers. The sheet metal fits (with the exception of the door strikers) but the body lines do not match up. There were also running changes to things like heater boxes, dash and instrument changes, and of course wiring changes.
If you like everything to match up, buy a complete cab and front clip, then you may have to buy a matching box as well. If you don't mind that the body lines don't match up, but want a truck that will still roll down the road and get the job done, you can mix match parts and make it work. I had a mix match Dodge 4x4 truck that served me very well for over 15 years. When I needed a body part, I found one in the best condition and bolted it on. My wife called it the calico truck, and my son's buddies laughed about it until he had to pull them out of the ditch, after that they understood it didn't have to be pretty to work. Gene