Can you tell by looking at the outside of a 489 carrier housing (minus the posi tag)if it is a posi or not?

It MAY have an orange paint daub on the drain plug IF it came with a Sure Grip & IF it has not had the daub added or the guts changed.

Check it, that is the only way to know for sure.

With the jacked up....both wheels turn the same direction when wheels are turned...when driveshaft is turned same thing....so a position for sure..right?

Yes its a sure grip. Positraction is Chevy's name for a limited slip. Sure Grip is Mopar's name.

I'd jack either rear wheel off the ground & bear hug it & crank it forward & see how difficult it is to break it loose (trans in neutral)

Do a burnout, only true test I am aware of.
_______no good

==========good to go

One possible outcome of that test is not knowing if you have an open or a burned up sure grip.

Jack the rear end up off the ground and put it on jackstands then try and turn one wheel in park if it won't turn it probally is a posi center, if the other wheel turns opostite of the direction your turning your wheel it is a non posi center section IHTHs If you put in any other gear but park and spin a rear tire and the other tire spins the opposite way, if the other tire spins the same way your turning and the driveshaft matches the tire rotation you have a posi

Yep. Even if it's an open differential it's possible to lay down two identical patches.

Burnouts prove nothing about nothing.

In a sure grip, if one wheel is on the ground and one wheel is jacked up, driveshaft disconnected, can you turn the tire by hand or will the clutches be too strong to release?

If the clutches are not burned up, or the cones bottomed out and offering no resistance, you will not be able to turn the tire on not on the ground without considerable effort.

Exactly, I've done it many times with an open rear

with a good forward bearhug you'll get it to let loose

I had a peg leg lock up, gears jammed and it was full posi. both turned and did double blacks on the pavement. It was broken.

That's something that happens to a pegleg after many ... and I mean MANY .... one wheel burnouts of insane speed and length. I took a one legger apart once where I had to use a hammer to assist the spider crosspin out because the spiders were galled on the shaft...

You must be ... \russian accent ... "STRONG LIKE BULL" ... or it's was a POS cone type that was almost toast ...

The break away torque cant be too much or the car would skid around corners. Wonder what that torque is.

I ain't sure double R, it was 30 yrs ago & it broke loose with a medium amt of effort & rotated forward several inches iirc. & I was thinking it was a clutch one. EDIT Johnfin I vaguely remember a torque spec of 150 lbs for em (should take (at least) that or more to move it)

hi, sure-grip cone clutch might slip... sure-grip clutch plate tight... sure-grip cone clutch machine and shimmed... very tight... ronnie