We have rebuilt FE3's on our compg and also used quickstrut dropins on our regal. Drop in was used because we were trying to put them together during covid, and we couldn't find the parts to rebuild. I am not sure if they are shipping them again yet. We were trying all the gm part suppliers, gmpartsgiant, gmpartsdirect, wholesalegmparts, etc.. all would hold our money for a week or 2 sending us notice that the order was delayed, and then eventually would cancel.
Definitely prefer the fe3s that we pieced together over the drop ins. We will be changing them again in the Regal assuming we can find the parts.
Check out this thread, SaukRapids posted part numbers and tool info for the fe3s we built for the compg.
2005 CompG - Back on the road. It's about time!
I don't have any experience with ZZPs.