I took mine in Friday, explained that when I have the bed loaded with heavy cargo that the drive and ride is very harsh and uneasy especially when I go over bumps, and also that it feels like it sags. 20 minutes later, the service rep came out and said they were going to order a new rear spring set for me.
I didn't mention the tsb because I was still in play-dumb mode, so i didnt ask if they were going to give me the 3+1 tsb spring cause I'm just still the uninformed customer to that dealer.
Edit--Done! What a painless experience and I got to use a free loaner for a day.