Old butter fingers (me!!) dropped this new, metal cased, fuel filter on the floor. It now rattles, from something inside, when I shake it. Have I screwed it or is this normal? Not sure if it rattled before.

https://www.summitracing.com/parts/hly-562-1

 

I would toss it and get a new one. They are not supposed to rattle. $20.00 spent is well worth the peace of mind.

 

+1 for toss and replace - should not rattle

 

steel cities gray ...

 

Switch to an OEM style fuel filter. It will be more reliable and maybe cheaper.

For example these are from turbocharged 300zx, same design as the one you posted (canister type) but larger.

I've used these filters on over 100 vehicles for 600-700rwhp in the past

 

That looks a lot like Fram pn G3870

 

Return it. Summit is good about returns.