1989 GMC Sierra 2WD, auto, 350

1989 GMC SIERRA
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BKING1505
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  • 1 POST
My truck makes a clunk sound when it changes from 1-2 and 2-3 gears (not the 3-overdrive) coming from the rear of the truck. I also notice a very similar clunk when I brake suddenly and the truck comes to a hault.

This truck has 230,000 kms on it. Is this the U-joint or rear differential? It doesn't sound like it's coming from the tranny more from the back but I'm no expert. I'm not sure if the braking clunk is the same as the gear shifting one but it sounds the same

Thanks for the help.
Apr 26, 2007 at 9:59 AM
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HBAUGH
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  • 8 POSTS
check the u-joints for wear by moving them up and down and left to right.
Apr 26, 2007 at 10:50 AM