[HUMMERcustoms.com/TAZ]

I do not know if this will help but these Gm 5.3 an 6.0 Litres are not good about holding oil in the top side of engine if you sounds like maybe it would b cheap to use an oil filter that You now has a spring that will holdback oil into the top end and see what happens. My 99 5.3L Silverado started a clicking type noise after about 5 months. I bought it Jan 99 new and as that 5 month speel began it had stated going into summer which made it harder to keep up oil trapped up high. I told dealer and He said Yea You have got to use an AC filter (as at that time) AC was only one with spring. I changed and noise stoped. Coincidence who knows? I got 153,000 miles and used synhetic and does not need oil between changes at 6,000 miles I expect to get 250,000 or maybe cross my figures 275,000 miles. Go figure!! I do know that most all better quality oil filters now have springs.
I have gotten 263,000 from 1989 Ford crew cab dually that was my driver but my farm truck also and that dirl went through Hell everyday it fired up. I sold it to get 99 silverado and the guy that bought it 6 years ago thill owns it and had put injetor pump. NO biggy as Ford had said that every 100,000 mile new pump and I put 2 on it before he put 1. This may not relate at all especially if noise started later in life. This problem I had started real quick and had quick fix. Dually cause of condition I put primer oilpump for top end and change oil every 2,000 miles. I'm hoping tht is what made it last well.
Rick
Oh sorry I was going to suggest a prelube oil pump that connect to bottom of oil filter adapter or bottom of oil pan sump it comes with usually what you need. Racers use them so You can get them anywhere. I just got lucky and on chevy the spring loaded filter solved my problem.