I have a 97 T&C mini van that broke the rocker arm shaft on the back head it is a 3.8L v6 would it be wise to replace the head or just the rock arm assem.

 

There is a repair kit, But I would replace the cylinder head. This has been a common problem with the early 3.3 and 3.8. If you do replace the head, be sure to get the right head gasket. Because the 3.3 and 3.8 are not the same. The 3.3 has a larger bore than the 3.8 and make a hell of a noise, when you have the wrong gasket.