Re: Rear Center Unit
[Re: Wolfe440]
#1151644
01/06/12 04:03 PM
01/06/12 04:03 PM
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Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT
Management Trainee
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Management Trainee
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
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Probably a 741 but it could have a 489...
"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."
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Re: Rear Center Unit
[Re: 1_WILD_RT]
#1151646
01/06/12 04:06 PM
01/06/12 04:06 PM
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Joined: Jan 2003
Posts: 74,974
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 74,974
U.S.S.A.
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Quote:
Probably a 741 but it could have a 489...
My 69 GTS 383 has a 489 .
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Re: Rear Center Unit
[Re: Wolfe440]
#1151647
01/06/12 04:08 PM
01/06/12 04:08 PM
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Joined: Jan 2003
Posts: 74,974
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 74,974
U.S.S.A.
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Quote:
Which is the better one?
the 741 has a smaller pinion stem than the 489 , butthe 489 has a weak crush sleeve vs the stepped pinion shaft. Both pinions are smallest where the outer pinion bearing slides on .
It's a toss up ...
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Re: Rear Center Unit
[Re: Wolfe440]
#1151649
01/06/12 06:24 PM
01/06/12 06:24 PM
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Joined: Jan 2003
Posts: 74,974
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 74,974
U.S.S.A.
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Quote:
I have a 657, I know it does not belong in this car, the yolk has a 1 1/8 u-joint. Will this yolk fit on a 741 or a 489? Or do both of those units come with a 1 1/8 u-joint also?
most 489's use a 29 spline yke , that 657 probably has a 10 spline , 741 can be either depending on when it was built .
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Re: Rear Center Unit
[Re: Wolfe440]
#1151651
01/06/12 07:20 PM
01/06/12 07:20 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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I believe the 741/742 have the same (very desireable) clutch sure grip unit itself which'll interchange w all 3 (including the 489 which OE has a cone sure grip). 4 diff pinion flanges 2&1/8 2&5/8 10 spline 29 spline
live every 24 hour block of time like it's your last day on earth
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Re: Rear Center Unit
[Re: Wolfe440]
#1151652
01/06/12 07:32 PM
01/06/12 07:32 PM
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Joined: Aug 2003
Posts: 43,123
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,123
Bend,OR USA
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Quote:
I have a 69 big block barracuda with an 8 3/4 rear end, I was wondering what sure grip center unit casting number this car should have. Thanks, Wolfe
Are you asking about the center section casting numbers or the posi unititself ? 1969 was the year that Mopar changed both, you could have a 721,742 or a 489 third member housing and you could have, depending on exactly when the car was assembled, either the Dana clutch type posi or the later GM style cup and cone type units 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Rear Center Unit
[Re: RapidRobert]
#1151653
01/07/12 12:26 AM
01/07/12 12:26 AM
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Joined: Jan 2003
Posts: 74,974
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 74,974
U.S.S.A.
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Quote:
I believe the 741/742 have the same (very desireable) clutch sure grip unit itself which'll interchange w all 3 (including the 489 which OE has a cone sure grip). 4 diff pinion flanges 2&1/8 2&5/8 10 spline 29 spline
RR the 741 spanned both the 742 era and the 489 era , those made before 69 had the clutch type , those made 69 up were cone ...
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Re: Rear Center Unit
[Re: JohnRR]
#1151654
01/07/12 01:49 AM
01/07/12 01:49 AM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Oh OK so the 741's had both. Didn't know that. Thank you double R
live every 24 hour block of time like it's your last day on earth
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Re: Rear Center Unit
[Re: RapidRobert]
#1151655
01/07/12 04:28 PM
01/07/12 04:28 PM
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Joined: Aug 2003
Posts: 12,291
Kent, Wa
340SHORTY
Truck Nut
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Truck Nut
Joined: Aug 2003
Posts: 12,291
Kent, Wa
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Never seen a cone Suregrip in a 741.. Must do somemore JY hunting..
I am truckless..
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