OK - after much input and advice from everyone - it looks like I have an IP going out. I will likely be replacing it and the timing chain at the same time. Chain has 300K+ on it so this is a peace of mind issue for me as well.

Big question is where to get the IP and what brand chain set. I've used a new GM pump prior and the one in there currently is a reman I got from Heath. I see that Delco sells a reman pump but also have others available through Napa (Echlin reman with 3 yr/36K warranty which is attractive) Advance and Autozone sell the A-1 Cardone brand. I've read some good info about Dtech and my local diesel shop sells these. Thoughts?

On the timing chain set - any big difference than anyone has seen with Cloyes vs. Sealed Power vs. Perfect Circle or others?

Thanks!

Brad