I believe the -3's with the endurance pkg were marked -3E. The -4 is the first model to have all of the endurance upgrades.

Back to the OP
Just for looking at, the 5 screw pre-models are by far the nicest. I have shot a gazillion rounds through my original 29 which is a -3 with no issues; however, I will say most of them have been more along the lines of a hot 44spl load. On that same note, since I dont really shoot hot magnum loads anymore I prefer the 60's vintage -2's for finish and reliable shooting.