Should i add lucas to my differential ?

[kcfirstbuild]

Should is use Lucas oil stabilizer in my differential with a quart of 80-90 or should i use two quarts of " lucas 80-90 gear oil" or just use two quarts of 80-90 and be done with it. I have 12 bolt on my 1968 c-10. I have been using lucas of a long time and just thought since i was changing the fluid out i might use some in the rear . but wanted to hear what everyone thought.

I'm going to stay away from synthetics, im not building a speed demon.