UPDATE: Unfortunately, as I was suspecting, it turns out the timing chain guide/cassette broke. As a result, the engine needs to come out. This, obviously, is a costly repair. I'm thinking the most cost-efficient solution would be putting in a used engine. I have access to a 2007 4.0 SOHC with 100k on it. What do you guys reckon?
In regard to replacing the engine, I hear the 2005 4.0 differs slightly from 2006-2010 (e.g., the flex plate and torque converter). Now, my question is: I can just swap those components over from my old engine and shouldn't have an issue, correct? Any advice would be extremely helpful.