5.9 Magnum valve train sound
Just going to throw this out there because I have seen it before: When you installed the new lifters, you remembered to install the "dog bones" and make sure the spider retaining plate was on top of the "dog bones"? I have seen people try put the dog bones through the loops on the end and get all kinds of interesting noises.
Also the "dog bones" have a top and bottom side. Putting them in upside down can make some funny noises as well.