Does the rear leaf TSB apply with the factory tow pkg.? 2013 D-cab TRD Off-Road Shortbox w/HD tow pkg. hauled a solid maple 6-pc. bedroom set with no sag, handled great...
Starting in '12, the Sport and possibly some other models started coming with the TSB leaf pack. There are some indications that Toyota is claiming to have redesigned the Off Road leaf pack. I haven't heard any solid confirmation of that, either different part numbers or a side-by-side comparison of differences.
That said, I have loaded up my '12 TRD OR, and it didn't seem to sag as much as my '09 did before I did the TSB on it.