489 Case 3.91 gears and 741 case 3.23 gears value?

[Mstone68440RR]

I came across a pair of used 8-3/4' rear end cases while helping a local lady sort through her storage. The stampings were 2881489 A and 2070741. The gears in the 489 case were stamped 2020226 3.91 and the 741 case 202064 3.23

From what I have been able to gather online the 741 case is the lightest duty 8-3/4" and was primarily in A body cars thru 1972, while the 489 case is the heaviest duty 8-3/4" case used from 69-74'.


What is the fair market value for both cases, and what is the easiest way to identify if they are Sure grip? I don't have alot of experience in differentials other than what I just looked up. Would the 3.23 gears be interchangeable in my 742 case? Or does the smaller pinion shaft prevent that? Thanks for any input in advance

 

[451Mopar]

The gears are unique the the case. Each case uses a different pinion gear size. An open diff (non-suregrep) should be easy to tell.
Here is a link with some photos of the carriers:
http://forums.moparmusclemagazine.com/70/7957918/mopar-drivetrains/8-3-4-rear-end-question/

I haven't bought or sold any in 20 years so I have no idea what they sell for now, I would guess maybe $300 on the low end for the 741 case 3.23:1 gears with an open carrier, up to around $500-600 for the 489 case 3.91:1 gears with a sure-grip in good condition?
I'm sure others will have a better idea of prices. I have seen some high prices at swap meets, but they don't seem to sell at those higher prices.

 

[ma mopar nutz]

450-550 depending on how bad someone wants them but that would be my price on them !

 

[terzmo]

323 suregrip go for 300 to 350...open....100....391 suregrip in 489 go around 500...maybe a bit more depending on need....

 

[Bigal75]

I'm interested in the 3.91 set up. Let me know...

 

[Cranky]

Years back I was told you could actually swap the pinions between the 41 and the 42 cases but with a bearing change which will constitute resetting pinion depth. IIRC, the pinion shaft bearing fit size is different so a bearing swap needs to be done. The only other thing I see different between the two is that the 41 has a spacer sleeve (NOT a crush sleeve) and the 42 has this as part of the shaft....manufactured in. I had always intended to check into this myself but never really had the need to. I also seem to remember that the carrier bearing ID's are different between the two but all the bearings between the three units use the same OD bearing race.