Correct rear axle?

[pbf777]

I would expect Mustang J codes with 28 spline 4 spd 9" and GTs autos maybe, but autos non GT using 8".

    Agreed. As I understand it, "non-GT's, w/ auto, & 3.00 and higher gears", got the 8-inch. 

Didn't all 31 spline traction Lok rears have 4 pinion diffs and 28 spline used 2 pinion diffs?

    Not sure of the breakpoints in usage, but I've witnessed "2" & "4" pinion examples in either spline count.

And Daytona pinion support came w/31 spline rear.

    The "Daytona" type was targeted toward applications which also incorporated the "N-case", and which also generally involved "31-spline" axles; but just note that 31-spline axles didn't necessarily mean you automatically got the others!  Just "never say never" with Ford.   

Ford was too cheap... whoops frugal/efficient to overbuild and they ruled Shelby in 68.

    And this was the frame of mind that started my inquiry!  And when you think about it, did a "J-Code" engine option in a little Mustang really need the "Big-Dog" 9-inch?   

    Scott.

[Coralsnake]

I can see Ford utilizing 28 spline 9" axles for GT350's auto and 4 spd - and I would expect Mustang J codes with 28 spline 4 spd 9" and GTs autos maybe but autos non GT using 8".

Didn't all 31 spline traction Lok rears have 4 pinion diffs and 28 spline used 2 pinion diffs? And Daytona pinion support came w/31 spline rear.

Ford was too cheap... whoops frugal/efficient to overbuild and they ruled Shelby in 68.

302 4V was a high volume build.

Its not really a debate what they used.

Its quite clear based on the build sheets and tag codes.

1968 GT350s were 31 spline cars. Period.

[warwick]

I must admit to sometimes getting confused with the 68 GT350-it all started with back in the day reading the I think it was Road and Track review of the 68 Gt350-it was a white one and had was it called I think "High Performance " package to soup it up and they compared it to a Z/28.........never heard or saw a 302 4V with a "High Performance" Package. Sounded great though.

Now you tell me the little 4 barrel 302 (not TP not Boss) had the same rear as a CJ/427/429....and Ford ate the cost, not only the parts but the assembly.. remember Daytona pinion supports had spacers (ie: shims) vs a crush sleeve.

Hmmmmm. Did the GT350 come with a C servo hipo C4 automatic?? How many tag codes and build sheets you got?

This is one time Ford really acted out of line.

[Coralsnake]

About 250 build sheets and probably 500 warranty tags. Shelby made the modifications to differentiate the cars from Mustang. Its why they also had the 3.89 gears

Cars magazine featured the GT350 that was a custom build with 302 "high output".

 
https://www.thecoralsnake.com/Curiousity.html

[warwick]

I ask this question out of ignorance:  was the Paxton supercharger a factory production option in 68 for the GT350?

3:89 's with a 302 4V sounds painful.

I would think the majority of the buyers wouldn't know the difference between a 28 spline/9" and a 31 spline/9"/daytona pinion support/4 pinion diff - not a great differentiating factor

[Coralsnake]

No Paxtons on 1968 production Shelbys

[TLea]

GT350 302 4V 31 Spline 9 inch   Was a J code 302 4V Mustang a 31 Spline 9" inch?

Shelby= 31 spline
J code Mustang 28 spline
3.25 and up 9"
3.00 down 8 inch