Please help verify/identify this third member.

[Gold Duster]

Can anyone please help me confirm/identify this third member which came out of a 1962 Imperial. I suspect it is a 8 3/4 SURE GRIP with 3:23 gears which is what the tag (not pictured) has stamped on it. Any help greatly appreciated.

 

[69 Sleeper Bee]

742 case is the stronger one for the bigger cars or HP motors so I think you are correct on your assessment.
You say you have the tag that says 3.23 and SG ?

 

[R/T Boy 67]

It is a 742 housing with a clutch type sure grip. The ratio should be stamped on the ring gear. It is a strong unit, and new clutches are available if needed.

 

[Gold Duster]

Yes, I have the tag.

 

[493 Mike]

The ratio is stamped on the ring gear also.
Mike

 

[Gold Duster]

The ratio is stamped on the ring gear also.
Mike

Thank you. I will double check when I head back to the shop.

 

[Gold Duster]

It is a 742 housing with a clutch type sure grip. The ratio should be stamped on the ring gear. It is a strong unit, and new clutches are available if needed.

Thank you!

 

[Jerry Hall]

Great unit, no matter where it came from.

 

[R413]

That is the best set up there is for an 8.75.
742 housing & clutch SG.

 

[YY1]

be careful interpreting the ratio on the ring gear

there are several numbers, some of which are valid or very close to valid ratios but are NOT the ratio of the gear

 

[Damien B.]

Quick question what make the 742 the most desirable case for an 8 3/4 third member

 

[Jerry Hall]

Some will say that the 489 housing with the 29 spline tapered pinion is stronger. I don't believe that, I stand with @R413 on that being the best 8 3/4.

 

[MoparLeo]

Same strength without the crush sleeve.

 

[R413]

Quick question what make the 742 the most desirable case for an 8 3/4 third member

It is something nobody talks about. The 742 pinion bearings are huge. Under acceleration the pinion is pulled back loading that front bearing. Also the 489. Has a 90 degree step in The pinion. The crush sleeve is a bad thing. Plus everybody prices the 489 highest so for all these reasons I just avoid them.

it’s not that the large pinion means anything, have you ever seen of a pinion gear breaking in half? The 10 spline yokes don’t seem to be a problem either.

Also in the mid 80’s when these cars were 15-20 years old most of the noisy rear ends had a 489 case.

 

[Gold Duster]

Wow, thank you all for the great information.

 

[Damien B.]

Thanks for the explanation. It makes sense

 

[YY1]

Gear selection for the 742 is the weak point.

741 and 489 have more ratios available and are easier to find.

 

[R413]

741 new gears are easier to find than 742?

 

[Gold Duster]

What's this third member worth?

 

[TN Mopar]

In my experience the 741 is getting harder and harder to find gears for
For example my recent attempt to rebuild my 741 with a 3.91 gear
We were unable to find a 3.91 gear to fit the 741 case
It is available for the 742 & 489 case
We ended up going with a 489 case so that I could stay with the 3.91 gear