M1028 Axle questions

[NMerenda]

1. On the Wiki it says only the 1028 require lsd additive. Wouldn't the 1031 also require it?
2. Do both axles get the additive or is it just the front, and how much additive do I need to add? Is it in addition to the existing fluid or is it factored into the amount the axle requires?
3. The wiki also says the axles require 90/75 gear oil, but I can't seem to find it anywhere. Is there a place I can find it or can I substitute a different weight? WEould a different weight hinder anything? And if I use synthetic fluid do I still need the additive?

 

[Recovry4x4]

1. On the Wiki it says only the 1028 require lsd additive. Wouldn't the 1031 also require it?
2. Do both axles get the additive or is it just the front, and how much additive do I need to add? Is it in addition to the existing fluid or is it factored into the amount the axle requires?
3. The wiki also says the axles require 90/75 gear oil, but I can't seem to find it anywhere. Is there a place I can find it or can I substitute a different weight? WEould a different weight hinder anything? And if I use synthetic fluid do I still need the additive?

1) Best advice is to look for the tag on the front axle. Not sure that the M1031 had the trac-lok in the front.
2) Just the front and frankly you would have to check the LO on amount.
3) 75W90 is quite popular, if your parts house doesn't carry it, change parts houses. Walmart has tons of it. I wouldn't go thicker in NY. Synthetic could probably get you down to 50 wt. Need to check the label on it having the additive.

 

[GM72K10]

M1031 has the trac-lok in the front as does the M1028a1-2-3

 

[Recovry4x4]

Got it. Now I know!

 

[NMerenda]

Thanks for the reply guys. I'm going to keep the weight heavier just because I'm not going to drive the truck in winter. Mainly going to be for off roading/work. Amsoil severe gear 75w90 is what I'll go with.