Greetings all…
Have found a 9", nodular case; 3.50 gear ratio third member for sale. Seller claims it’s from a '66 Fairlane. I am wondering if this is a straight swap unit for my '67 GT with a stock 9" 3.00 rear end.
Thanks,
Follow up question…If the 3.50 gears are posi, will that affect the installation into my conventional rear end?
I think as long as the splines on your axles are the same it should be no problem.
It will bolt in, things to double check before starting are as Allen68 said, Spline count. Yours most likely is a 28 spline unit. Most Factory Nodular case units were built with 31 spline axles for added strength. You will also need to check the yuk. Ford used several efferent ones, If it is not the same get the instructions from a shop manual before just swapping it over. You may want to have a shop do that. You also will want to get a proper driven gear for the speedometer cable and put that in so your getting a fairly accurate reading. I have done this swap a few times. Remember the center section is HEAVY.
Yes, I suspect the spline count will be the issue. I’m not hell bent on the unit. I just thought it might be nice to have a N-case with 3.50 gears if I could get it for a good price. I appreciate all the good information gentlemen.
Thank you so much,
Dennis
I believe the only Fairlanes in 66 that got 31 spline axles were 427 cars, there were only 57 of these cars made.
I believe the only Fairlanes in 66 that got 31 spline axles were 427 cars, there were only 57 of these cars made.
If it came from a '66 Fairlane like preaction said it would most likely be a non - nodular, 28 spline unit. Better get some photos of it and post here so someone can tell what it is that you are actually buying. If it is what the seller states it is worth many thousands of dollars. Usually sellers overstate what they are selling, I have yet to be surprised by how great something was that I paid a fair price for.
This is the only picture I could get.
The ad originally said that it was from a Fairlane, but the description the seller sent me in an email says…" 9 inch 31 spline, 3.50 gears in N case. Has the larger side bearings…probably came from a Galaxie".
Thoughts…?
Its got a March 14, 1969 date code and the big squared off “N”. Could have been in any number of 1969 model year cars and trucks including Mustang, Cougar, Comet, Fairlane / Torino / F100 etc.
Thanks Royce. I have already passed on it, so I am not even sure what the asking price was. I’m pretty confident that my C6 has the 31 spline shaft, but I can’t believe that my current stock 3.00 conventional rear end has anything but 28 spline axles. This unit is not so important to me that I would consider replacing the axles as well just to accommodate it.
I appreciate your time and comments…thanks.
Dennis
Thanks Royce. I have already passed on it, so I am not even sure what the asking price was. I’m pretty confident that my C6 has the 31 spline shaft, but I can’t believe that my current stock 3.00 conventional rear end has anything but 28 spline axles. This unit is not so important to me that I would consider replacing the axles as well just to accommodate it.
I appreciate your time and comments…thanks.
Dennis
I might be interested if you could forward info or find out the price?
I am certainly willing to follow up for you, but know that the unit is here in Calgary, Canada. Shipping might kill you…
Let me know either way…
Dennis
If you don’t care about the Ford numbers. For the money you’re better off with an aftermarket unit like Yukon. The bearing caps are heavier. I’ve used this seller: staticz2229 on Ebay with real good luck. Then you can add the Eaton TruTrac 
Thanks for this…!
Always pushing the Eaton stuff…
I don’t recall ever seeing a forum post where someone blew up an 8" Ford axle in anything less than and all out drag race with some very big HP numbers. Has any one ever had an 8" that failed in street driving? The reason that I ask is that I am contemplating putting a set of 3.89 rear gears in my son’s '68 XR-7 behind a built up AOD. It is powered by a mildly build 351 that I would like to one day build into a 427 stroker motor. It might see the drag strip once or twice but would mostly be street driven. I am wondering if there really is any reason to go 9" as that will involve a lot more expense for maybe no gain.
Without re-reading the thread, being his car is an S code, it should have a 9" originally. Or am I missing a bit of info?
I think you would be fine until you got the 427 stroker in it (good low end torque) and some sticky tires. One of the main reason to go 9" is parts availability and cost. If the cost is the same do a 9" for added strength. I don’t think you need the 31 spline axles unless you were to go 4 spd and doing hole shots. The 8" & 9" 28 spline use the same axle. I have 3:89 gear in the track cat with the 28 spline axles and Trutrac with 600hp and tremec 5 spd. But, I have alum flywheel and driveshaft so no low end Inertia is being applied. I don’t need the power in first gear and it rev’s faster then I can shift it exiting a corner.