I have a 2002 5.9L auto tranny. Everything is awesome but the transmission it slips in and out of over drive between 45 and 55. Ivery annoying and I'm not fixing it till it completely gone. Any year is good but get a manual transmision. Don't settle for an auto like I did you will regret it.
That is most likely not your tranny, probably an APPS sensor. I've got the same deal happening on my truck, it causes the torque converter to lock and unlock, which makes it feel like your tranny is slipping.
