My 06 e 350 cargo van sounds like a diesel after timing chain was replaced ? It's a 5.4 GAS MOTOR
If you hear rattle,then timing chain is not tight,or there is a bad timing idler.
I hope they replaced the guides and hydraulic tensioners while they were there, it could be the variable cam timing units they can also make a noise like that when they go bad. Get a mechanics steascope and try to locate where the noise is, if it is down in the chain cover then it could very well be a bad tensioner but if it is up on top then is could be the VCT's themselves.
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