Getrag fluid
 

Ok so I know over fill a quart to bath the front bearing but I put a cummins in my blazer and I got the motor and tranny running at 7 degrees (not temp lol)I was wondering what the average first gen runs at degree wise and would it be ok to maybe go a quart and a half over full just for a good peace of mind:humm: oh and what type of oil should I run hope everyone can help

The manual recommends 5W-30 motor oil and says you never have to change it. Not surprisingly, these transmissions have a reputation for failed input shaft bearings. Many people advise overfilling the trans by half a quart to alleviate this problem. I believe this masks the actual problem, which is that normal 5W-30 motor oil can't handle the shearing action of the gears and thickens over time, causing poor lubrication splash/flow. I think the lube needs to be changed more often than never (well, duh). but cant advisr on an alternative oil

I always change mine at 7K miles or when ever I run the trans temp over 300F. It surprising how much metal comes out after 7k.

is amsoil too thin to run in this tranny?

Is there any friction additives that I should have and is synthetic ok to use?

5/30 is 5/30 no matter syn or dino. Most motor oils will contain friction modifiers unless they are designed to also run in wet clutch situations.(atvs, motorcycles, etc.) but is should say right on it if it is.
A synthetic is a bit more heat and shear stable so could offer longer protection but as Whit indicates, nothing lasts forever

Why not like 10-40

has anyone added an additive with zinc and phosphorous?
I changed the oil in my suv tranny and T case with synthetic and added some new engine break in additive just cuz.