Rear springs/shackles bushings...

[MagnuM4WD]

Hi! I have a "little" problem: the new rear springs (56"), comes with factory rubber bushings fitted on (1-3/8" bushings, fitted in 1-3/4" outer sleeves, fitted in springs eyes - after I measure the diameters on the springs, I assume they have the dimensions mentioned above!). My question is: to keep or not keep the factory rubber bushings?!
If I decide to replace them, what type you recommend me to use (1991 Chevrolet V2500 Suburban Silverado): 1-3/8" bushings in 1-3/4" outer sleeves, fitted in springs eyes, or 1-3/4" bushings fitted directly in springs eyes? What kind of bushings are better (small or large OD)? There is any differences between Suburban and Suburban Silverado rear springs/shackles bushings (I saw on some sites, some mentions about!)?!