I found the info in the archives a little confusing. There was a printing date for each map in addition to publication date. I don't think the printing date implies that anything actually changed on the map, just that they ran off another batch when the supply was low. You would need to track each quad through the years and compare to find out any changes (they were usually done in purple ink).
USGS has really dumped these maps and now only considers them "historical documents", you can no longer download the actual maps from them, just geoPDF files from the historical archives. That makes them a pain to work with, you need to extract the map image from the PDF file, then crop the collar before actually doing anything. And there's a crazy range of colors between different maps. Many of them have bright yellow forest shading instead of green. It's not clear whether the ink changed color as it aged, whether there was something weird about the scans, or if some maps really did have yellow forests!
The older DRG maps (that were used by NJGIN as well as the old Terraserver website) are no longer available from the USGS, although you can still find them here and there on various state websites. I wanted to make my own regional 24k USGS topo and last spring I downloaded about 30gb of maps from NJ, PA and NY. Started assembling them into a seamless map, but when I looked closely I felt the quality just wasn't good enough. Ended up trashing everything I downloaded and giving up.
Even though they're a pain to work with, the USGS historical topographic map archives is the only place to get high quality scans of these old maps.