Fleet farm generic 80w-90 went in mine. Gear oil is gear oil. I also put an 08 cover on it.

You will need a press, and I went with new carrier bearings. Far better than trying to press the old ones off.

Check the backlash before you pull dnr carrier and after installing the true Trac with the cast iron shims. If it is still within spec you are good to go. If not, you will need a set of shims and adjust it until the backlash is correct. It shouldn't change the pattern but you can certainly check it before and after. That is if you aren't replacing the gears. Throw it all back together and let er rip. You don't even need you take the wheels off to do it.

Oh and press the ring gear onto the carrier don't draw it on with the bolts

 

The shop that did mine used Redline lightweight shock proof synthetic 80w140 in mine after the 500 mile break in. Supposed to keep it about 15 degrees cooler. Along with the aluminum cover now also. Should be quite a bit cooler. It's quiet, both tires leave brown strips in the grass. Seems to grab right now when I step on the gas. Loving life with this.