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1973 ford f100

I can’t figure out why my truck at 40 mph to 50 mph rattles so much I jus got the wheels balenced not to long ago. I’m thinking it’s the driveshaft since it was replaced about 4 to 5 years ago. I had a buddy at work tell me his dads when he was a kid did the same thing so if anybody out there can give me some insight on this subject please tell me.

Are you willing to get under the truck and inspect the U-joints and driveshaft? I really don’t understand the logic when you say since the driveshaft was replaced 4or 5 years ago so it must be bad now?

U joints would cause vibration rather than a rattle.Is the whole truck shaking?

It’s more of a vibration than a ratle but when I put it on a lift about 7 months ago I had a certified tech look at the u joints and he said there fine what I mean the driveshaft was replaced my grandpa replaced the original driveshaft when it feel out.

Is this new software mixing up words?

No I’m doing this on my iPod touch

Then explain why you think your driveshaft could be the cause of your vibration,and are you willing to get under your truck and check things out?

Is this thing 4wd or 2?

2 wheel drive

I had one probably 15 years longer than I should have, It was a rust bucket and it felt like on sharp turns it wanted to go 2 different directions, though it did not rattle. If you could try to clarify what is going on that would be helpful. What part of the truck does the rattle seem to be coming from, are there specific conditions that cause the rattle, what are the symptoms when you experience the rattle, for all we know it could be a bad or missing exhaust clamp

It feels like it starts from were the cab is

I am moving on,good luck.

Maybe a transmission mount and possibly still a bad U-joint.
Putting a vehicle on a lift and trying to wiggle the driveshaft by hand to determine if there’s a bad U-joint is not always a 100% valid test.

Sometimes the driveshaft must be dropped to check them. It’s very possible to have a binding/rough joint that will not have any looseness in it.

And there’s always the possibility of a bad center carrier bearing.

True very true looks like imap have to do something thanks

If the rear of the truck is lower than it should be, you can have too straight of a pinion angle. That will ruin U-joints because they have to flex a little so the needle bearings can rotate back and forth to stay lubricated and not flatten out from wear. You can replace U-joints.