still new to this MJ thing

[wutangwisdom]

under the new 88 mj and noticing a big black boot behind the rear shocks anyone elnighten me to what these are my driver side one looks true but the passenger side looks crunched a little

[HOrnbrod]

Most likely bump stops. 

[wutangwisdom]

no they are round about 2 times the size of the shock

[Wesleypipesyo]

Can you post a picture of it?

[wutangwisdom]

maybe a diff style

[sinkrun]

air lifts?

[Megadan]

Sounds to me like air helper springs.  Bags that you inflate with air when carrying heavy loads.  Pictures definitely help.

[Eagle]

I'll add another vote for air bag spring helpers. Not a factory option.

 

As has been said, photos would help.