Had the indy look at the noise in the back suspension.
Yep, the rear-most bushes are indeed shot completely. The front-most ones are in decent shape (ie, have not failed).
My indy knows that I can't spend a ton of money on the truck, and has suggested just replacing the two failed ones.
The posts here talk about replacing all four at once.
Does it make any sense to replace just the two bushings that failed and then wait for the others to fail in (x+ months)? I'll replace with OE rubber, instead of the powerflex fwiw.