hi i have a 98 blazer with 95k. when i shift my truck into reverse from park there is a loud "TINK" noise coming from the back under the suv. also when i drive on the express way the truck shakes very bad about 60 mph. i am trying to figure out what u joint is bad but i am not to sure on how to check them some people say to jack up the truck to check them and others say to not jack it up. also is it suppose to be in park or neutral? how many u joints does this truck have? and does bad u joints have anything to do with hard shifting from 1st to 2nd? also are transmission flush recommended for these suv's? and if so should the filter be changed to because the mechanic shop doesn't include the filter with the flush.

Thanks for the advice and help.

 

I would imagine your blazer is similar to my 98 s-10. If so,there are 3 u-joints- the drive shaft is in 2 pieces. You should have enough ground clearance to scoot under the vehicle(in park/pbrake on/level) & shake the drive shaft. If there is no play and it is not apparent which one/s are loose. I would jack up the rear end with the frount blocked and set jack stands (never ever trust hydralics). With the pbrake off and the t in neutral you can rotate & shake the drive shaft to determine which joint/s loose. There is also a drive shaft support that also may be sloppy. Not familar with the tranny mine is a stick.

 

I did finally replace the ujoints on the drive shaft but when i put the truck in reverse from drive i hear a loud TINK noise coming from inside of the transfer case. do you have any idea what this could be. also when i slow down it make the tink noise in the transfer case. i know it is coming from the tcase because i had someone under the truck when i put it in reverse from drive and the said it was coming from the transfer case. any ideas would be great thanks.

 

The gears or chain in the transfer case could be worn and have excessive play in them.