NP229 Vacuum leak in 2wd, goes away in 4wd High

[jettfuel]

I recently swapped in a used NP229 and noticed a bad sound(like the chain had too much slack inside the case)in 2wd above 55mph, it didn't do it before the swap. Also I have a intermittent vacuum leak from what sounds like the actuator while in 2wd, but goes away if I slightly pull up on the High/Low lever or switch the vacuum switch from 2wd to 4wd High. Once into 4wd High the vacuum leak goes away and so does the vibration/grinding sound above 55mph. Any Ideas? I have a Haynes manual and am pondering over it now but I don't know where to start.

[90wag]

I think I've got a vacuum problem similar to yours. I get a hiss coming from the area of the 2wd/4wdhi switch on the dash. It goes away when I give it gas or when I pull up slightly on the hi/lo lever under the seat. I've never noticed if it goes away when I'm in 4hi though. My system seems to be working fine, no trouble engaging 4hi or low so I'm thinking it's a leaky vacuum line to the dash switch. I posted here about it and the advice I got was to check the lines to the switch (just to be sure, I'm going to replace them)if the lines check out fine or you replace them and the leak continues, I would get one of the handheld vacuum gauges that the Haynes manual shows and test the switch itself. The Haynes manual explains this test in pretty good detail. Sorry I can't be of more help but I hav'nt had the time to dig into this myself yet.

As for the slack chain noise in the 229, I havent had that problem yet.(KOW)
Dave