Rear axle ID???

[Hart_Rod]

Anyone know what this is? Is it a posi? What year?

[68C10HotRod]

It's a GOV lock as they call it.

[Hart_Rod]

Are they any good? What are they worth? What did they come in?

[LONGHAIR]

They are "marginal" at best. In purely stock form and with calm driving, they can last a while.....but if you drive like that, you really don't need a traction device. Adding power, wider tires, or hard use will kill one pretty quickly.
When they go, it's "catastrophic", that is why they are usually called "Gov Bombs" or "Gov Pops". I refer to them as "Timex Posi" for 2 reasons; the tiny internal watch parts, and because you never know how much time you have before it blows.
When one fails, the small parts come apart first, and get between the bigger ones. I have not repaired one....and never would.

[Blazer1970]

That is an Eaton Automatic Locker as supplied stock by GM in many trucks. They are not intended nor are they any good for doing burn outs.

[Jacfourteen]

The problem with these units is that they are open under normal conditions, then when one tire spins about 100 rpms faster than the other the rear changes to fully locked all at once. This is fine if you are in snow or gravel or some other low traction situation, but if you are on pavement or have a heavy load or whatever the non-spinning tire is firmly planted and instead of it catching up to the spinning tire the small internal parts go snap followed by the big internal parts going BOOM. I have one in my 01 tahoe and I'm sure to go easy on it. I have a friend that had one in his 03 1500 and he tried pulling out someone that was stuck, his failed bad enough that it split the housing nearly in half. So like stated above they work fine for normal driving, but more power or burnouts they won't last long.

[LONGHAIR]

Once again.... they NEVER completely "lock-up" the "Loc" part of the name is purely marketing hype (BS). The centrifugal mechanism acts upon a ramp that applies pressure to the clutch pack. So it is basically a "variable pressure" clutch-type posi.....that has a built-in self-distruct mode.
It does NOT lock any more than any other clutch-type posi unit can. A true locking differential is a competely different animal.

[Jacfourteen]

Originally Posted by LONGHAIR

Once again.... they NEVER completely "lock-up" the "Loc" part of the name is purely marketing hype (BS). The centrifugal mechanism acts upon a ramp that applies pressure to the clutch pack. So it is basically a "variable pressure" clutch-type posi.....that has a built-in self-distruct mode.
It does NOT lock any more than any other clutch-type posi unit can. A true locking differential is a competely different animal.

Are the newer ones different? I read my info off of another site but it was about the newer version. I know when I have the rear off the ground on my 01 tahoe if you spin the wheels there is no resistance at all, then once you spin it fast enough to engage the mechanism it makes a loud clunk, then the wheels seem to lock and then they bounce back the opposite direction. It seems like if it were clutches then they would just slow down, but I don't know.