1966 Mustang Driveshaft end

F

Forder

Senior Member
I'm working on a 1966 Mustang A code 4 speed car. I took off my driveshaft to change ujoints and the joint on the rearend side gave me issues. The New U joint was just slightly too wide to fit. I compared the new U joint to the old U joint and the new one its just slightly wider. Like a 1/16" of a Inch. The new U joint Part number is #498. I tried napa, O' Reillys, and a local parts store, whom all gave me different brand U joints, all with the same part number, but they all were wider than the old U joint. So I took the driveshaft to a place that specializes in driveshafts and they insist that my driveshaft end that holds the U joint has been bent in and that is why the new replacement U joints won't fit (even though the new u joint is wider then my old one) and they want to change the end on my driveshaft, however they "can't get" the original style end for my driveshaft so they want to put something else on. So I have a few questions

First has anybody run into this before ?

Does anybody make the correct U joint ?

Where can I get the correct replacement end for my driveshaft ?
 
never saw that but anything is possible.i was thinking that a bearing needle had dropped but im sure that has been checked.
 
If its bent in, it will bend back out. If its not a high horse power car, it should be OK. If it comes apart later, then spend the bucks for a new drive shaft. Big hammer, one darn good whack in the correct spot, measure carefully.
 
Seems weird that a "place that specializes in driveshafts" can't identify your existing joint, if the 498 is wider.

Measure the widths and cap OD's and check the specs on the other 3 joints O'Reilly lists for a '66.
 
Try another driveshaft shop. Any/all that are within a reasonable drive. I don't think the first place gave you an acceptable answer.
If the ears of the driveshaft yoke are bent it would vibrate while driving, and your existing u-joint probably wouldn't fit easily unless it was damaged to match. If the car is a non-running project then their 'bent' answer could be easier to understand.
With any luck you can eyeball that yourself by putting a long straight-edge against each/both ears of the yoke to see if they're parallel with the driveshaft, and both sides should be the same.
I'd think if an ear is bent 1/16 it will be real obvious at the far end of the straight-edge.
(example photo below, watch out for odd lumps in the yoke casting)

Do some detective work and find out what part number/Mfr existing u-joint you have, that already fits, and get one. (see my next post)

Just guessing here.....
Are you sure it's the original driveshaft for the car? Is there a difference between the 3spd, 4spd and automatic versions? Would a 6 cyl driveshaft have a slightly smaller diameter and a different u-joint than one for a V8? Maybe one got swapped in as a quick 'n dirty substitute in the distant past.
 

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