This has probably been addressed already, but here goes...

I have a Ram 250 5.9 L6 Cummins, 70K originial miles. I am towing about 6,000 lbs (Jeep on trailer) and I can only get 40-50 mph on decent hills and it starts to get hot 3/4 on temp gauge. I have changed the filter to a True Flow and noticed some difference. What else can I do for an improvement in performance. Also anyone know what gears this truck has.
(2wd Supercab,longbed).

All answers are appreciated.

Thanks,

 

It shouldn't be getting hot, i'd adress that before i did any upgardes. Once that is fixed bigger injectors, turbo upgardes and eventually a better fuel pump. But two much performance can damage the tranny.

 

please post in the cummins diesel section....

https://dodgeforum.com/forumid_143/tt.htm

you will have more help from us diesel guys....

 

I agree - address the heat problem first. Don't overlook the possibility of poor heat transfer in the radiator. I'd start with taking the radiator to a good shop.