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Discussion Starter #1
So doing some research looks like there was more than 1 type of u joint on the mustang drive shaft. To confuse things more looks like they switched types in 66. My car was built in Sept 65 and is labeled 1966.

So how do I measure the u joints?

I measured with a tape measure and got 3.25" across on the rear one and little over 3.55" on the front one. I know a tape isnt the best for this but just need to close enough to tell with I have. Or so I thought.

But what I'm seeing online there is a 3.21" front and a 3.6" front and rear so I'm confused.

Thought about buying them local but $25-30 vs $8 online is a huge difference so going to order once I know which I need.

Thanks
Stephen
 

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So doing some research looks like there was more than 1 type of u joint on the mustang drive shaft. To confuse things more looks like they switched types in 66. My car was built in Sept 65 and is labeled 1966.

So how do I measure the u joints?

I measured with a tape measure and got 3.25" across on the rear one and little over 3.55" on the front one. I know a tape isnt the best for this but just need to close enough to tell with I have. Or so I thought.

But what I'm seeing online there is a 3.21" front and a 3.6" front and rear so I'm confused.

Thought about buying them local but $25-30 vs $8 online is a huge difference so going to order once I know which I need.

Thanks
Stephen
The only difference I noticed was retainers on the inside vs the outside, manual vs automatic, i6 vs v8. If you know all those things, any parts store should be able to help you out.
 

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Discussion Starter #3
Thanks for that info. Mine is a v8, manual and it does have the clips on the out side holding then in the drive shaft
 

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Once you know the width across each pair of caps and the diameter of the caps it is easy to determine which u-joint you need. I know of an online vendor who will not sell a u-joint based upon the car it is going in. He will only sell you a u-joint when you give him the measurements. Apparently there were mid year changes and even changes depending upon which factory the car was built in. And 50 years later who knows what a PO may have changed.
 

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I just went through this issue on my 66 coupe while trying to source the u-joint locally. After going to several shops and not finding what i needed, i posted up at the NAPA counter with a knowledgeable and willing bubba with my old u joint and calipers. The source of my issue turned out to be incorrect data in the online parts catalog that o-reily, autozone, and napa all used. The u-joint i ultimately purchased measured correctly in hand, but reflected a different width measurement in their computer. I can track down the napa part # that worked for me if you need it. It was for a 289 2/v with auto.
 
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