I've got a '96 F350 which was beat hard in the oil field. In 4wd I get a popping when under heavier load. I suspected the 3-bolt lockouts so I swapped them w no change. Thus I think it's either front r&p deflection (highly unlikely and no leaks at pinion seal) or something in the t-case, probably the chain.

I once had a guy tell me the chain in his 1356 would slip, but I never believed it. Has anyone else seen anything like this?

No symptoms in 2wd.

Obviously no one had any input here.

Update: I swapped this case w another 4407 I had lying around. The symptoms seem to have disappeared. I have not (and probably will not for some time) opened up the offending case, so I don't know for a fact that it was the chain.

Between the last time I dropped a 1356 and today I've had back surgery. The 4407 sure seemed damn heavy to me but I figured maybe it's just the fact that I've very much adjusted my personal limits for what I will manhandle. When all was said and done I weighed the 4407. It came in at 117lbs! Compared to the 1356 at 72lbs, that's a considerable difference.

Also I was surprised to see the 4407 drink almost 4 quarts of ATF (vs approx 2 quarts for the 1356) before it was topped off.

The 1356 at 72lbs:
http://www.supermotors.net/getfile/78918/original/bw1356-002.jpg

The 4407:
http://www.supermotors.net/getfile/702832/original/bw13562-065.jpg

The shift fork on my 1356 wore out and did exactly that. It would deflect under load and pop. Eventually it just kicked out of gear all together. And always in the worst possible situation.

The shift fork on my 1356 wore out and did exactly that. It would deflect under load and pop. Eventually it just kicked out of gear all together. And always in the worst possible situation.

Absolutely. And I've seen that, but this just felt different. Again, I only had symptoms in 4wd. The shift fork in the 1356 always locates the slide gear within the planetaries (or not), so in that instance it'll also pop out of gear in 2wd.

The fact that I only had symptoms in 4wd, and only when I'd load up the drivetrain led me to suspect things which are only engaged and only involved with turning the front output.

Plus, this condition did not seem to be getting any worse. The truck was recently used extensively for months climbing a nasty north-facing, snowy hill with chains on all 4. It would "pop" when climbing but never seemed to increase in frequency or severity. And it never actually popped into neutral. If it were a shift fork I would have expected something to eventually let go, or get worse. It just strikes me more as a chain somehow jumping a tooth (but I can't confirm that).

Plus I have not actually seen the internals of a 4407 so perhaps it was the shift fork. I'm only ass-uming it's overall function and operation is similar to other BW cases such as the 1356 and 1345. From what I've seen even the internals of an NP208 aren't all that different from the 1356, IOW most chain-driven cases are similar internally. But I do wonder what all the extra mass of the 4407 accounts for?

Anybody here opened up a 4407? I suppose a '96 Helms manual would have an exploded diagram........