Your attached pic looks like someone cut a crude replacement out of heavy rubber, below is what the original looked like.
#14281-78010 - MOUNTING, CENTER PIPE, discontinued, replaced by #14281-60G01
#14281-79010 - MOUNTING, MUFFLER, discontinued, replaced by 14281-60G11
As you can see the "sleeves" are a part of the mount, originally bonded to the rubber - you can order them from megazip.net, but the shipping will be more than the parts - RockAuto has generic replacements, and so most likely does your local muffler shop, or just go ahead with the sawed off pipe nipples
#14281-78010 - MOUNTING, CENTER PIPE, discontinued, replaced by #14281-60G01
#14281-79010 - MOUNTING, MUFFLER, discontinued, replaced by 14281-60G11
As you can see the "sleeves" are a part of the mount, originally bonded to the rubber - you can order them from megazip.net, but the shipping will be more than the parts - RockAuto has generic replacements, and so most likely does your local muffler shop, or just go ahead with the sawed off pipe nipples