My shackles too tight?

Installed
Dakar leaf pack with nitro chargers 2 years ago
Greased really well

Developed a rubbery squeak this year
Took it apart to clean/relube bushings and leafs

Question is what can cause my bushings to be worn out?
Still had lubricant inside
Stock shackles
I did torque all bolts after vehicle was on the ground 2 years ago

2002 tacoma

 

So I don't know anything about Tacoma leafs, but on my Samurai I have steel sleeves inside the bushings that prevent the bushing from smashing in. I feel like you're missing those, but maybe I'm just too inexperienced of a home wrencher.

 

IIRC there is metal sleeves that go inside. I know there is on my second gen Dakars, but cannot recall my first gen.

 

I installed OME Dakar leaf springs and OME bushings, for my stock shackles, just last month on my first gen; the bushings came with metal sleeves for sure.