I am changing a bad valve spring on my LS1. I bought a OEM spring from GM (honeycomb type). I pulled the bad spring and found a second spring underneath. The retainers I have are much larger than the one needed for the honeycomb spring. So here's some thoughts.

1) The prior owner put aftermarket HP springs/retainers in.
2) The prior owner did this to match a aftermarket Hp cam.

I have no freaking way of knowing where the parts came from unless you bright guy's have some ideas!

The spring I need looks like it had a 1.840 installed height
and is a double spring with a 1.260 outside spring diameter
My thinking is SLP parts. Ron