Your Burlington F-3 set dates from 1980, which in my opinion, is one of the best years of MPC production.
The body detail question was covered earlier in this thread, but here's the info again:
1979: The return of the portholes and nose grabs.
1991: The return of the two-piece horns (I think this is what you meant!), side vents and screened roof vents.
1998: The return of the nose vents.
1999: The elimination of the bottom ridges.
Your set doesn't have the nose grabs because of the nose decal. The electronic horn was first issued in 1981, as was added to F-3 B-units. (They even made a kit to do this.)
The Pullmor motors used in your set are essentially the same ones used in postwar production, starting in 1955.
I hope this helps - enjoy your set!
