Its a 2003 chevy 1500 ls z71 So I've been noticing a vibration, it feels like its coming from around where the trans meets the engine maybe the torque converter. The vibrations happen at around 2000-4000 rmps. It doesn't happen every time I'm accelerating. It doesn't really make the truck lag to much but I'm just curious what could be causing it.

 

How does it operate at idle in gear?

 

it works good at idle

 

Check the rear u joints?

 

the u joints are all good but when I first start the truck it does have a small knock or tick I always thought it was the engine cause it goes away after a few seconds when the engine starts warming. You think it could be the flex plate? I did inspect the flex plate and did see any cracks but I didn't take the trans out

 

the u joints are all good but when I first start the truck it does have a small knock or tick I always thought it was the engine cause it goes away after a few seconds when the engine starts warming. You think it could be the flex plate? I did inspect the flex plate and did see any cracks but I didn't take the trans out

 

The 5.3's are notorious for snapped bolts along the exhaust manifolds especially on 7 & 8. It usually sounds like a bad hydraulic lifter tick and once those manifolds and heads heat up it will go away. Had 2 broken bolts on my 2001 and replaced both manifolds. Look above the manifolds and you might see black markings where the manifolds meet the head from where the exhaust escapes. If you have to replace the manifolds, don't use the Fel-Pro gaskets, they are junk. Went with a copper alloy header gasket on mine. https://a.co/d/7VmiYdJ. They work great!
That ticking will worsen over time and at higher RPM and load, it will get worse. Mine started sounding like an old tractor!