My buddy has an 04 dmax crew with the juice attitude.6in lift and 35 in tires.when he pulls his 26 ft trailer sometimes(quite often)the trany slips.between 1st and 2nd even 3rd and 4th.He has the edge on 1 or 2 doesnt seem to matter.Truck has about 18,000 miles on it.A cold air intake and after market exhaust,Other than that and the edge its stock.He has also started complaning about a loud growling noise when going down hill and trucks brake comes on.I personally have not herd this yet so cany explaine it very well.just wondering if anyone else has had these typw of issues?
Thanks

The slip sounds like a flare during the shift. The adaptive shift strategy of the Allison should eventually tighten these up, but if he is making large swings of power and load, it will have some difficulty.

Could be the fan clutch engaging when rpm and air flow drops...