I've seen a couple of 2003's that were produced late 2002 with non hardened 4th gear hub shafts.
Likely the shaft is stripped and that's why there's no 4th.

Poncherelli... I think they are talking transmission fluid temperature. There IIRC is a temp at which the trans defaults to 3rd gear in an effort to have you drive slower and get it's heat back down.