I recently started having problems with my Dana 35 that has 3.07s in it, so now I am on the road to rebuilding the rear end and re-gearing. I am staying with the Dana 35/30 combo and going to upgrade to the Eaton Trutrac front and rear. My question is what size gears should I run. Most of the time I am driving around town with an occasional freeway trip. I am torn between 4.10s and 4.56s and leaning towards the 4.56s? Please help. I don't want the engine to be turning high rpms to run 80 on the freeway but I also don't want any problems if I go to 35s either. Let me know what you thknk.

Ax15 and 4:56 is what would be recommended. I recently did the swap from 307 to 456.
Rpms Will be around 2800 at 65 to 70 miles an hour.

4.56 for 4.0 with 5sp and 33's. You should stay away from 35's if you plan to keep the Dana 35 axle. HTH.

Take care.

4.56 but I would not recommend putting money in a D35.