I have an 87 ChevySilverado long bed that has been running fine until about 2 days ago. It started knocking at first it was quite now its pretty loud. I crawled under the truck and it sounded like it was coming from the tranny but not 100 percent sure (I am not a mechanic by any means). The ticking is only when the truck is at idle, if I sit in the driveway and put it in gear it still makes the noise, but if I put it in park or in neutral and rev it up the ticking goes away. My dad suggested it may be the torque converter. Any suggestions???????

 

if your truck has a catalytic converter u need to check the heat shield it could be loses and making that knocking sound