T-5 and rear end fluid
 

Will these work out for me in my 90 GT w/114k miles? It has a t-5 and is a 100% stock daily driver. I believe the t-5 and rear's fluid have NEVER been changed!

-Redline D4 Synthetic ATF
-Redline 75w90 Synthetic Gear Oil
-Ford Friction Modifer (for rear)

Will these cause me any problems?

Also, do all 90 GTs come from the factory w/ limited-slip? I know the factory recommends Dexron III ATF in the T-5, not sure of rear end fluid weight. Please help.

Those fluids will work fine. Your Mustang does have a limited slip, but whether or not it still works is another story. The traction-lok could probably use a rebuild after that many miles. Take it out and see if you can get both rear wheels to spin when you take off from a dead start.

Re: T-5 and rear end fluid
 

anyone else?

First, I confess to being a true synthetic nut! That said, I recently installed a new Auburn differential in the 89. The instructions that accompanied it said to definitely NOT use synthetic fluids in the rear end. It recommended a good 85/90 gear oil and the Ford friction modifier. I have no idea why but that's what it says.

food for thought.