As far as I can tell the springs are the same type. The kits come with instructions that have been photocopied too many times..... I doubt any real thought has been put into this design in the last ~50 years. It's VERY old technology. I worked for a compressor repair and manufacturing company and rebuilt MANY Quincy recip compressors - quite a few were from the 1950's and 1960's (mind you this was about 2007) and came out of naval and coast guard ship applications, military bases, and tons of industrial applications. Be glad they used a disc valve compressor - much more long lasting and reliable than the consumer grade reed-valve crap that is used in every home depot and craftsman garage compressor. And *usually* doesn't result in catastrophic failure - of course my own example being the outlier in that regard. But that goes to show how much abuse our trucks lived with in their service life. My truck had 2,750 miles on it when I bought it. About 5,500 miles when the compressor failed. Come to find out the dryer cartridge was original from 2008
These perform fine when properly and timely serviced. They just never got that in their former life and they are often still overlooked in their current life.
