Have an 04 2500HD, rt. rear spring isolator has broken again (2X). On my way back to dealer to get new one under GM's dime, after that I may fix right with end caps.

However I noticed that the lower spring on the left side sits away from the main springs while the right is very close to the above spring. Left spacing is 3/4" on front and 1" on rear, while right is 1/4" and 3/8" , respectfully.
It is possible that the right spring is bad, are there any TSB or docuemnted problems on these springs? If the spring is defective I would like to get some info before I make life difficult for dealer.

There is no TSB that I'm aware of. There was a rubber cap that they were adding back in 03 when I was having the spring slap issue.
Had the springs sag on my 2002. Found this out when determined the drive line hum/drone I was having was caused by the drive line angle being out of spec. Ended up re-arcing the springs to 3500 spec and adding an additional leaf. The re-arc was done under warranty, and I had to kick in for the extra leaf. Thought it was better to do it right the first time. The ride did not change much and it handles my trailers alot better.

Before I visted the dealer, measured the spring on both sides and found the drivers spring down by 1/2 ". Good news - the dealer said that's right and will order a new spring!
Bad news (maybe) - they will only replace the single spring, when my Fords did this sag stuff Ford always replaced as a set. I'll just wait and see how it works out. Thanks for help

If the dealer is going to order a new spring, I was told by my dealer that they could only order the full spring pack. That is where warranty steped in and said they would only re-arc the existing springs. The dealer allowed me to talk to the suspension shop about how I wanted the re-arc done. i.e. true heat treated not just re-bent. That is when I also went to the 1 ton spec on the re-arc and the additional leaf. My truck has not sagged at all since I had them redone and I have pulled/carried some heavy loads.