Early 3.9 Diff is better than later one?

[launieg]

I just took a look at the rear end on my '78 parts car (manufactured May 78) and was delighted to see it has the 3.9:1 differential. (Yes, I am very slow at examining what I bought last fall )

So the first question for you is "will the trailing arms be the same as in my '81? I would think they would be, which gives me a solution for my one bent long trailing arm (a swap).

The second question is "will this be a better quality diff than in my '81? I understood that the manufacturing shifted to Spain at some point and the quality dropped. But did this happen during the manufacturing life span of the 3.9 diff? I'm hoping that this early 3.9 will be a good replacement for my later one at some point in time. (It sounds good when driving the '78.) Thanks.

[mdrburchette]

According to my parts book, the trailing arm is the same. The only difference between an early rear end and a later one is the panhard bar.

[pope]

I had both, apples and oranges. Earlier ones are a little faster off the line where the later ones are better at the high end (highway cruising).