86 K5 Rear End question

[Justin Fleming]

Hello

My 86 has a stock GM rear end. I drained the fluid as it had water in it and wanted to replace it. I noticed that when I pulled the back cover it apperas that the truck has some sort of lock up mechinizim in it. It seems as it is a open diff but probably at speed this mech. slings open and become a sliper or locker of some sort.

What fluid needs to go back in the rear end?

thanks

 

[Muddytazz]

Put in a fluid designed for limited slip diff's

 

[sta500666]

It should say in your owners manual if you still have it. Or just go to your parts store like advanced auto or auto zone, and tell them you have a limited slip diff. they will tell you what you need! Prolly need 3 or 4 to fill it up.

 

[mudboggink5]

It might be a posi unit, they have some type of aditive you can put in with the gear fluid. You can get it at napa or autozone

 

[3/4 Ton Blazer]

It sounds like you have the factory eaton gov-lok differential. If you put it in park, and raise the rear end, and just spin one tire as fast as you can with your hands, it should lock up. I would call the dealer to ask if it requires any special fluid, I cant remember off hand.