Iron rock off-road leaf springs

Just got my IRO leafs, and I'm about to install them but there are two different thicknesses of bushings....

All are the same size diameter wise, but 4 have a thinner 'lip' on the outside and 4 have a thicker 'lip' if that makes any sense...

Not sure if I'm supposed to use one thin and one thick per end or what?

Anyone have any experience with them? I can post pics if needed...

Never mind! Figured it out....

Another question though, should I grease up these poly bushings or leave me dry??

grease them liberally!!!!