1968 9-inch Rear End on Mustang GT

[GTCSMustang]

Teamlo,

Thanks. I updated the trans/engine combos. Does this look correct? C6 only avail with 390 and 428. 3-speed manual trans available with 200, 289, and 302?

Thanks for the input.

Scott

 

[GTCSMustang]

I have updated the matrix to the best of my ability without additional information. If there is no information listed I do not have a Marti Report to suppot filling it in.

Does anyone have an X-code Mustang with GT option?

Anyone with a 6-cyl with 4-speed man or C4?

Anyone with 302-GT with 3-or-4-speed manual trans?

Anyone with X-code 4-speed?

Does anyone know if the 390 cars came with 28 or 31-spline axles?

Thanks,

Scott

 

[teamlo]

Additionally, 4-speed was not available with the 6-cylinder engine in 1968.

 

[teamlo]

390 X-code would have 9" ring gear, not 8". Also, if memory serves me right, the 6-cylinder cars would have come equipped with a 7.5" integral carrier type rear axle as opposed to a removable carrier style (8" and 9"). Someone please correct me if I am mistaken.

Terry

 

[GTCSMustang]

Terry,

I updated per your comments (thanks). I show it as 7.25 not 7.50 ring gear diam., and with 24 splines. That sound right to you? Deleted the old matrix.

Scott

 

[teamlo]

Scott,

I would also take out the 4-speed with the X-code 390. The C6 was a mandatory option with this engine.

Terry

 

[GTCSMustang]

Terry,

Change made. Thanks.

Scott

 

[GTCSMustang]

OK. I think I have confirmed all the information in the matrix except for the yellow areas. I don't actually know if you could get a 302 GT with a 3-speed manual. Any help on the yellow areas would be appreciated.

Scott

 

[GTCSMustang]

OK. I think this is almost done.

Anyone have a 6-cyl with a C4? That's the only box I need information for.

Scott

 

[gt bandit]

Hi all

I have a NON GT 68 CS equipped with J code engine package , C4 and 9 inch diff standard from factory with 3:00 gears. In fact I still firmly believe that J code cars built after April came equipped with 9" regardless of other options.
That build date is something else to ponder.

shaun

 

[gt bandit]

I am also sure that if we had Pauls long awaited book , this mystery would be solved !!!

keep going Paul

SHAUN

 

[teamlo]

Scott,

I would be hesitant to call the 390 X-code a "non GT" in the matrix, because you could in fact get the GT equipment group with the X-code 390 2V engine.

Terry

 

[GTCSMustang]

Terry,

Do we have any Marti reports for GT vs non-GT X-codes? Or do you think it's the same axle ratio for both?

Scott

 

[teamlo]

Scott,

I will do some searching to find some Marti reports for GT X-codes as well as non-GT X-codes. There may be some posted on this website, but I can't remember how to get to them for viewing. My understanding is that by and large, the X-code was really more of a "highway cruiser" type powerplant, and was actually a Cougar engine option for 1968 that was later brought over to the Mustang line to gauge interest in the option. Not many were sold ultimately. The few Marti reports that I recall seeing for the X-code 390 Mustangs all had 2.75 (or perhaps 2.79) axle ratios. Not a high performance powertrain by any means, but a smooth all around performer with the 2V carb, C6 and low numerical axle ratio. Definately more than adequate performance in a Mustang.

PS...........I sent you a PM concerning a J-code, 3-speed manual 1968 GT.

Terry

 

[J_Speegle]

OK. I think this is almost done.

Anyone have a 6-cyl with a C4? That's the only box I need information for.

Scott

Scott

The Marti's I have with this application show a T code C4 with 2.83 gears. No way of telling if this was a typical/standard order or not.



Also have X codes with the listing

68 X code with automatic and GT package -"5 3.00 Standard axle ratio"

and others with

68 X code with automatic no GT package listed "1 2.75 Standard axle ratio"


The "standard" does not describe the standard gear ratio just that it was hot a traction lock. For those looking at their buildsheets

Hope this helps

 

[GTCSMustang]

Jeff, Terry,

Thanks. Martix updated. Do either of you know if the 390-2v or 390-4v used 31-spline axles? I'd guess that maybe the 390-4v GT did, but don't know.

Scott

 

[teamlo]

Scott,

My guess is that the 390 cars (S and X) used 28 spline axles. I believe the 428 CJ cars were all 31 spline. But don't quote me!!

Terry

 

[rvrtrash]

Hi all

In fact I still firmly believe that J code cars built after April came equipped with 9" regardless of other options. That build date is something else to ponder.

shaun

Sorry to disappoint you. My J code was built May 15th, is a non-GT, and has an 8", 3.00/1 rear end.

Steve

 

[robert campbell]

Heliaster,
If you can get under the car, there is a tag on the forward side of the rear, normally on the passenger side on a bolt that holds the "pumkin" in. Provide me that info and I can tell you if it is an 8 or 9 inch.

They are easy to tell apart if you have seen a bunch of them. If you don't have a tag, we will resort to measurements. Code "E" is a 3.00 limited slip.

Do you have a Marti report? If so, is it listed in the option portion of the deluxe report, which is in the bottom left hand portion of the page.

To all,
If it was an option it could be checked. We can deal with the norm, but don't get to absolute. For instance, the 4 speed option on a 6 cyclinder was not an option in 1968. So that is an absolute. Ratios and axles are subject to the option sheet, especially if upgraded to the trac lock.

Rob

 

[murf104]

My non GT April 03 build date car also has a 3:00 eight inch rear. Not aware of any information that cars built after April 01 68 have a 9 inch as standard.