Truckzilla: rear shocks

Mileage somewhere around 137k.

After a few bouncy rides and a visual appraisal, I bought Rancho9000XL shocks for the rear end.

Here's the old left rear shock as it came off:

And a disconcerting close-up:

It's interesting that the UPPER housing would rust thru.  I saw a recommendation online to NOT install the gators on the Rancho's on the grounds that they fill with water, which - rather than guard against corrosion - accelerates it.  I assume the same thing must be going on here; I left the gators off the Ranchos.

I cranked them both to 9 and took a test drive.  I didn't notice a big difference, but I didn't bounce, either.