742 and 489 rear chunks question

[shadango]

I found what I thought was gonna be IT.....a whole rear end (less brake hardware and drums) for a 66 Charger......3.55 and suregrip. 

I assumed it would be a 742.......turns out its a 489.

The 489 cases were later, werent they? IE, this axle is from a 66 charger but the chunk has been replaced...right?   Or did 489s go back that far?

[Moparal]

489 is the newest. Someone installed it. It is a good unit. All 30 spline

[shadango]

I am looking specifically for the 742 because I want the rebuildable clutch-type sure grip, and also dont want to deal with the crush sleeve stuff (I know they can be replaced with a spacer)...

[Moparal]

I have a 489 with a clutch. But I built it myself. And used doc differentials solid sleave in it. Works very well.  You do know a good cone sure grip will last years right?  As level headed as you act, I would think that either system will be good for you. You seem to go the extra mile on taking car of what you have.

[shadango]

Thanks Moparal.  Dont know that I am skilled enough to build my own.

I know that a cone type will last, especially under the use I will be subjecting it to.....but I am looking at used so I wont have a good idea of how good it is......and I have heard that refurbishing a cone type , while doable, is tougher.

Didn't know that a 489 could use a clutch type?  thought that 489s had to have the cone type and the 742 had to have the clutch type....therefore figured that if I could find a 742 with suregrip, it would have the clutch type already in it, and if it needed rebuilt, at least it was one that could be readily rebuilt.

I know....I think about stuff too much....LOL.....but I think i will hold out for the 742/clutch type a while longer......I am eager to get the rear chunk swapped in, for sure.....could just spring for a $1000 unit from Dr Diff....and still might.....

Ideally I would find a 742 with clutch type and 3.55s, in nice shape ready to drop in for a low price.....LOL......that requires a perfect alignment of all the stars.

[tactransman]

If you get a used 489,you have a very good chance that it will be worn out. I understand where your coming from.