Here's the thread on the same question I asked a couple of years ago. Jerry said "don't worry".
Monroe's website lists the 33049 as correct for the rear of a 3100.
Also, I don't plan on making my truck "catch air" so I don't think I'll worry about it. I questioned the position of the lower shock mounts and everything I saw (including the FAM Section 4 sheet 1.00) was that they pointed downward below the springs (that's the way they came to me.) One could reverse them and gain a couple inches on the shock length.
