What axle is this?

[BlaineKaiser450]

  its in a 1969 plymouth satellite that was being set up to be a drag car (but never finished) BTW. My dad and i think its a locker too.

[rt green]

83\4

[Just 6T9 CHGR]

83\4

I concur

[rt green]

see if the casting numbers end with 489

[mikepmcs]

if you can get it, get it!  no telling what's in that chunk. 
all three cases are fine 741 742 or 489.  489 might be stronger but nothing wrong with a 741.  I don't however suggest a 741 in an all out drag car though, but for normal everyday street and some abuse 741 is just fine.  It gets a bad rap though.

v/r
Mike

[BlaineKaiser450]

its a 741. It was already in the plymouth when we bought it

[hemi-hampton]

Isn't Locker a term used by the Ford People

[Ghoste]

More specifically, it's a form of limited slip differential that borders on being a non slip.  It is still made today by Eaton and Ford offered it as an option in the 60's but only the real heavy hitters typically ordered them for the street.  So you're right, because Ford used them it tends to be thought of as a Ford term but I can live with that better than Chevy's "posi".  At least the Ford one wasn't something that Ford designed or built, they just offered it.

[Mike DC]

The axle in the pics is the Mopar 8.75" like the other guys have said. (Mopar also built a totally different axle in that era called the 8.25" so don't get that confused.)

This one is the Mopar version of the Ford 9" basically.  It's about as strong as a Ford 9" too. (Particularly before the Ford ones are modified up the wazoo.)  Mopar axles didn't get any better than this except the huge heavy Dana 60s that only a few stick shifted 440 & Hemi cars got. 




The "489" and "741" and "742" numbers that guys are saying here  . . .  these refer to the casting number of the big removable iron chunk in this axle.  The 741 is weaker and the other two are virtually a tie. 

The basic sheetmetal housing of the 8.75" axle works with any of the 3 iron carrier castings. 

[squeakfinder]

I'm still not convinced the 741 is all that bad. It doesn't seem like I ever hear about people destroying them. 

[Ghoste]

It kind of got a bad rap from the Direct Connection/Mopar Performance axle bulletin where they recommended the 489.  I think it was more an issue from the days when all three were readily found why not use the best one?  For the most part and for all stock or near stock applications, they are all "best". 

[Mike DC]

     

Yeah, you don't hear about the 741s getting busted because people just don't run them that much.  The 742s & 489s far outnumber them, they've always been much more aftermarket supported, and they're painless swaps. 



The 741 isn't a piece of sh*t though. It's a decent piece.  Go ahead and use one if it's available, but just don't spend very much money on it.