trail master 4 inch lift, shock.size??
 

Having.trouble getting new shocks as i am not familiar with the size my truck.needs. it has a 4 inch trailmastee lift and currently runs trailmaster ss shocks. Do i need to buy a longer shock? Thanks for any help.

You can measure the front/rear shocks you have and match it for the collapsed and extended lengths or look up the lengths in a Rancho catalog and add 4 inches.
Rancho Suspension: Rancho® Product Catalog

A factory shock wouldnt fit with a 4" lift anyway.