The transmission upgrades offered here will completely change the way your Duramax LLY performs. Whether you're trying to keep it cool or you're looking to take your Duramax LLY Allison Transmission to the next level, this is the place for you. It is hard to describe the feeling of a built trans until you've been in a built trans truck. You won't regret the upgrade! Don't forget about a deep pan for your Allison in that Duramax LLY, these are a great, cheap upgrade that helps make that Allison last.