Does towing package equal 3.42s?

[Yukon John]

hey yukon

for this...Heavier Duty Brakes ("JD9" includes 17" disc)

they are HD, but not that big.
i have that code & my brakes were 13" & 13.6"
i have yet to see any SUV/truck w/ brakes that big, the upgrades are 15" or 16"

should it be maybe 17" wheels?

I agree...probably a typo in the RPO spec print out.