Going to look at a used pig later this week. It a 3.23 with a clutch suregrip. Other than obvious damage to the gear teeth is there anything else I should look for? Gonna use some dye to check the pattern but that’s about all I could think of. Any suggestions welcome, thanks.

Check backlash by grabbing the yoke with one hand and rocking the ring gear back and forth. Proper backlash is about .008 so you should feel a little slop. This check is just to ensure it’s not way out of spec due to problems. Also try to push the yoke in and out, there should defiantly be NO slop there. Look down the axle splines for visible damage (a flashlight would help, and make sure the plug is still in the center...meaning you can’t see all the way thru.
look at the carrier bearing retainers and locking clips for damage...if there is damage that’s a sign someone’s been working on it at some point,
look at the shur grip unit to make sure the pinions are properly located in the “V”’s and no damage present.

Very cool pacnorth, let you know how it goes, thanks!

Find out what case, on the bottom left side is the case number. What are the last 3 numbers 741.742,or 489. There are pluses and minuses to each one. 741 is under rated because of a supposed weaker pinion shaft. Not true, but the available new gear ratio’s is very limited. 742 is good because the pinion preload is set through shims. As is the 741. No crush sleeve that can lose preload and once you have the needed shim thickness you can remove the pinion to replace the seal and just tighten the pinion nut. 742 has a good number of new gear sets available. 489 is good, but uses a crush sleeve. You can get a kit for it that converts it to shims fir preload. The different pinions don’t matter in regards to strength. 8 3/4” don’t really break the pinion. They hammer the carrier bearing caps and knock the adjusters out.

Sorry for the slow reply. Turned out it’s a 741 case, suregrip is cone not clutch. Very little backlash slop, about .008-.010, however pushing the yoke in/out there’s about .050 play. Looking down the axle splines the plug is still there, retainers and clips show no damage. It’s a 3.23 gear set, that’s what I’m after, what’s required to get rid of that yoke play or can I run with it? This is for highway cruising, no dragstrip.

0.050" play on pinion yoke means complete rebuild and inspection for damaged parts.
If I were going to use it, I would throw away the gearset. Only exception I can think of is if, for some reason, the yoke was removed, then re-installed finger tight; but for that you had better have a solid history and record of any work.
Most probably, though, it's junk.
Plus, a cone sure grip is not rebuildable. I am not as negative on the cone type as many people, but, if it's very used, it's not worth using for the short life it may have left.

Robert

Check how tight the cones are per the service manual. It they are not tight enough, just have .050 or so shaved off the small end of the cone. That will stop them from bottoming out and allow them to grab the tapers again. I have done this several times with good success. But the center section needs to be cheap enough to justify the extra time and effort.

If you get it cheap enough (150) and the gears are in nice shape, you would be better off buying a new suregrip unit from doctor diff. Then you won't have to worry about anything, put it in and drive. https://www.doctordiff.com/8-3-4-clutch-type-sure-grip-powr-lok.html

Sounds like an early A-Body suregripper.

Most ‘cone units’ I have dis-assembled have been worn away to slipping.
Once this happens, the diff becomes ‘open’ and the spiders weld themselves to the centre shaft!

Everything can be fixed, but why waste time and money on a 741?

Peeps spend thousands on engines, maybe a grand on the trans and 100 bucks on the axle lol...

My motto is, “start at the back and work forwards”...

50 year old diffs are ‘worn out junk’

True-Trac every time for me...

3.23’s are the best alrounders but I prefer 3.73’s myself.

Except for the part about spider gears occasionally welding to the shaft, the above post is long on opinions and short on facts.

The OP said that this will be a street car, not a drag car. The 741 and cone will do that job if it's in good shape. I would not want it on the drag strip with drag radials, but it could be fine on the street even at it's age.

Update...so I grabbed the 741/3.23 case, guy’s car days were behind him so he threw in an open 489 case with 2.76 gears. Just what I need, more parts laying around! I’ve rebuilt the 489 case clutch suregrip in the Dart so looking forward to taking a run at this one. Found a pretty good post https://www.forabodiesonly.com/mopar/ams/how-to-recondition-a-sure-grip-cone.28/ that should help.