Stick with what I got, or try and find a "742"

[cruzer67]

I have a "489" case with an open 2.70 ratio installed in my 1967 GTX. The original setup was likely a "742" with 3.23 gears and a sure grip. Should I just install the 3.23s and sure grip in my existing case, or should I continue to look for a "correct' case to keep the car more original? It's unlikely I'd find a correctly dated case anyway.

 

[Darter6]

The 489 is the most common now that they make parts/gears for.
742's are still around,don't show up as often but are getting pricey.
If you have the 3.23 parts stick with the 489

 

[Jerry Hall]

Very debatable subject. I like the 742 case better than the 489 and my opinion would be to find a 742. A 489 is a little more difficult to setup, but again just my opinion. I to like to keep my cars more original and yes it came with a 742 gear.

 

[Rishi]

As with most things, I make do with what I have on-hand, until I find something better. Look for a 742 case, but don't let is stop you if you have the parts on hand for the 489 and can make that work without a great deal of effort, expense or patience.

 

[Outsider]

Man I would think you would be able to find a 742 with 3.23s, as that is like the most common car ratio for that era. How about the Spokane swap meet?

 

[cruzer67]

Man I would think you would be able to find a 742 with 3.23s, as that is like the most common car ratio for that era. How about the Spokane swap meet?

Unfortunately, Spokane is 8-9 hours away. I didn't expect to have this much trouble finding a 742, and when I have, they've been back east and most won't ship.

 

[PurpleBeeper]

Dude....just find whatever 3.23 posi center section you can find & keep your existing center section as is. That way you can swap any time you want. Any of the center sections will be fine. Also, there's a guy selling a 489 pumpkin with 3.55's in right now on this site

 

[Don67Satellite]

I have a "489" case with an open 2.70 ratio installed in my 1967 GTX. The original setup was likely a "742" with 3.23 gears and a sure grip. Should I just install the 3.23s and sure grip in my existing case, or should I continue to look for a "correct' case to keep the car more original? It's unlikely I'd find a correctly dated case anyway.

The original in my '67 is a 741 with 3.23 open, not sure when 742's started.

 

[Rishi]

taller ratios, such as the 3.23 are a tad scary in a sure-grip scenario in the rain. With a hard-shifting B&M Trans Kit 727 tranny, the back end breaks loose (albeit on a curve, even a mild one) in the rain with light throttle and has given me a scare or two before I learned to anticipate the loss of traction in the rain. I've since read BFG Radial T/As don't griu all that well, either.

 

[cruzer67]

I believe it has to do with engine size (and maybe how heavy the car is). Mine has a 440, and that's why I'm pretty sure it received the heavier duty 742.

 

[Cranky]

I like to dump that crush sleeve from the 89 and go with the solid spacer and use shims to set up the bearing preload. Dr Diff has the solid spacer and shims.... I also like to use a dab of red loctite on the pinion nut when I'm done.

 

[MoparLeo]

742 Very strong, easier to setup, no crush sleeve needed.

 

[DGE330/NC]

The original in my '67 is a 741 with 3.23 open, not sure when 742's started.

all 3 of my 67's have 741's in them

 

[threewood]

741 in my November 68 built GTX.

 

[Darter6]

Never had a 741 break or a 742 ,489. All good.

 

[Daves69]

I believe it has to do with engine size (and maybe how heavy the car is). Mine has a 440, and that's why I'm pretty sure it received the heavier duty 742.

Info here..............

The 1970 Hamtramck Registry "1969 PLYMOUTH, CHRYSLER & IMPERIAL TSBs Index" Page

Like Cranky says...............

Mopar 8 3/4" (8.75) 489 Case Crush Sleeve Eliminator

Mopar 8 3/4" 489 Case Crush Sleeve Eliminator

www.doctordiff.com

 

[dadsbee]

Your car came with a 741... I have a 66/67 x 741 x 2:94 sure grip in the back of my 69 Bee out of a charger. If I haven't broke it dumping the clutch for 43 years it ain't gonna happen. I scattered the OE 742 x 3:23 in 1979!

 

[copper67sat]

My 67 Satellite hdtp, 383/4, 727, 3.23 SG came with a 742 case. 67 Belv II conv, 318, 727, 2.94 Open came with a 741.

I traded some parts to a buddy for another 741 years ago that I think is a 3.23 SG - hard to remember now - that I swapped into the Belv. Not sure what it came out of, but it has a larger yoke so I needed a hybrid u-joint.

 

[copper67sat]

The Satellite also has a trailer/tow package so I don't know if that's why it got the 742.

 

[cruzer67]

Ironically, I just found a newly listed 489 that has new 3.55 Yukon gears and sure grip. He said he built it for a car he just sold, and never got it installed. he wants $500.