Sounds like the side window needs some attention paid in a couple of areas. Most likely problem is that the window channels are shot. Should be a snug fit all around the perimeter of the window frame (a 50 should have a metal frame all the way around the glass that contacts the channel). Next place to look is at the regulator (easier said than done - easy to tell when it is shot as the crank has lots of backlash). My bet is on the channel . . . these are not that tough to replace.
As far as the windshield is concerned, if the window rubber is cracked - easiest fix is to pump crack full of sealant. You can buy windshield sealer in a caulking tube. Take the inner frame/garnish off to relieve the pressure and pull rubber away from glass and squirt away around the area of the leak. Do the same between the rubber and the truck body. Wipe down with a rag with a moderate solvent (I have used ATF to clean up followed by soap and water) Having put glass into lots of AD pickups for friends - biggest leaks I have found come from no sealant used between metal and rubber on the top and the water following all the way around and then showing up in the lower window corners.
