Thanks to all the folks with the good info on here.
I've had a light 'jingle' in the drive train for about half a year, not really sure what to think of it at the time (was thinking front half shafts) i let it go.

A few weeks ago, driving home, the jingles turned to intermittent wacks, some i could feel thought the floor. I clicked it into 4hi doing about 40MPH on fairly dry pavement, previously had no issues doing this, and something started to make an awful loud ratchety grindy machine gun paced bangs. I quickly turned it back to 2WD and it went back to the jingly wacks, I continued on to drop off my buddy. Pulling away from a stop, still in 2WD & going straight, the sound started again like a slow (ping, ping, ping, bang, bang, pop, pop, grind, band) as i got up to speed. I drove it home and parked it, only drove it when i needed to.

2008 FX4 4.0 W/ BW1354 mileage: 160,XXX

Now it doesn't do it all the time, i can click into 4hi at a stand still and go slow and its not terrible still jingles wacks, that never goes away. So I, in all my wisdom, knew it was the transfer case and tore the BW1354 apart. Looking at the thing nothing seems bad at all, not sure how loose the chain should be, thought that was maybe the jingle? I noticed the boot on the cup end of the front drive shaft is torn, so maybe the half shaft like joint on the front drive shaft is the culprit? I kinda shot myself in the foot in tearing it all apart before doing a simple 4WD brake stand. I did run tires that were worn to different sizes for a time could have caused some damage.

I'm going to replace the front driveshaft but not sure if the transfer case needs anything

So a couple questions going forward:

Could the T-case chain make those pingy bangs at looooow speed, from a crawl?

If i replace the chain, do i need to replace the 'sprockets'?
I've not seen anyone really talk about replacing those, just the chain, with bikes at you want to replace everything as a drive-train kit, so it wares together

Any chance I'm not even close and its the diff?


Looking at the t-case sprockets it doesn't look like the chain slipped on the teeth the way I thought with the machine gun sound and all. Though it does look like it may have struck the inside of the case.

Thanks for the help.