I've had best luck with Moroso blue rubber with steel core. Fits in all the machining marks and let's you really tighten it down. Just make sure your pan bolts or studs are long enough because it's quite thick.

Follow my G3 Hemi Barracuda build on Youtube
https://www.youtube.com/watch?v=XSDAWczXoZw&list=PLTus_wQu8POADHEeJNJp2nr4NMHEyB9EK

2015 Tri-State Stock Super Stock Champion
2017 Monster Mopar Pro Winner
2018 Monster Mopar No Box Winner