Hey good folks

The Ranger is having some driveline problems..

Started a while back when off-roading aggressively. When engaging 4 High or Low there is loud clunking, scraping and clicking. When in 2WD the symptom mostly goes away. But there is still a rattling sound and some driveline chatter.

I first thought it was a bad front differential and replaced it.. But the problem persists. Now I believe it must be the transfer case gone bad some way or another (Maybe chain?) I checked the case and found the seal to be leaking, I was actually down 1 quart of oil. Filled the oil reservoir but that did not change anything - the damage has been done

Worth looking at the chain or just replacing the case? I can pick from one of two t-cases locally for $200 each

Thoughts?

My truck is a 3.0 with 5 speed manual, electronic t-case
The local t-cases are from 1) FX4 Level II 2005 with 205,000km 4.0 or 2) Regular 2006 with 230,000km 4.0

Looking for advice from those who know better than me.. Are the 3.0/4.0 automatic/manual transmission t-cases all interchangeable? Anything else I should check first? Yes the u-joints are tight

Cheers -Lawren