1. Is a 1987 t-5 on a 2.3 engine world class or not?
2. Are the main cases interchangeable, world class vs non world?

 

Are you asking about a Ferd? Because this isn't a Ferd Forum.

A Ford 2.3 in 87 with a T5 would be WC. As far as interchanging cases, I would tend to think a person would need to know all the details about the donor and the receiving cars. Generally speaking, I'd think it'd be a better bet to find a part from a donor that matches, since it eliminates a lot of potential pitfalls.