Hello, I have a question about my rear differential. I assume that the fill plug is the one that is on the cover, and when I refill, fill it to that plug. Is the drain plug the one that is on the bottom of the housing facing down toward the ground? Also, I tow a 5ver, around 11K, and was thinking of using the 75W-140 grape juice. Is it OK with the load I am pulling, or should I just stick with the 75W-90. I plan on sticking with the grape juice and maybe getting it from one of the supporting vendors. Thanks for the help.