98.5-04 trucks use a 3.5" down pipe then that runs to the muffler, then 4 inch out. 04.5 and up have full 4" all the way

 

My '05 has 5" outlet, but everything is 4".

 

12 VALVE!!! =Bullet Proof. Always use diesel rated 15-40 oil, and change it every 5,000 miles. Buy your fuel from a high volume Name Brand Station, change the fuel filter at least every 15,000 miles or when ever you note any reduction in power on a hard pull.

If you get an automatic transmission, up date the torque converter and transmission at a GOOD SHOP THAT KNOWS THE DODGE TRANSMISSIONS.

Sit back and drive it for another 300,000 + miles.

Ralph