I know this is probably a useless thread but, I want to know if anybody is running the 3.9 rear end with a TII setup. How much more top speed would actually obtain? Is it worth the 1 second loss 0-60?

 

First, the 3.9 is an NA diff, and won't bolt up to a t2 driveshaft.

Second, I've used the 3.9 with a manual in my convertible. It made the car too luggy. I thought Id save a bit of mileage with it, but as it turned out the car felt a bit uncomfortable most of the time, resulting in more throttle being required, so that didn't turn out. Also, on the highway where hills or curves are present, I found myself constantly switching between 4th and 5th around 70mph. The car was too weak to stay in 5th, so you had to go to 4th more often.