I know it's not 73-87 (91), but it is a Chevy truck...
2005 Chevrolet 2500HD, 6.0L, NV4500 and NP261HD transfer case. There's roughly 90,000 miles on it; mostly highway miles, many pulling a heavy trailer.
Since new, there has always been a bit of noise from the transmission. However, fairly recently there is more noise and I think it's coming from the transfer case and through the t-case shifter.
When going down the highway, it might start making the noise and then I'll let off the foot feed for a moment and the noise will quite down some. Also, I can place light pressure on the t-case shifter, moving it to either detent and the noise subsides.
With job relocation last winter and house hunting and 3 months of back and forth driving, I did a whole lot more driving in 4 wheel drive. Shift on the fly worked fine then. Somewhere along the way, I have lost shift on the fly. I can shift into 4-hi from a standstill, but it wants to grind if there is forward motion.
I haven't driven the truck much since we finally got moved back in March. I did notice with the last oil change (this spring) that when I turned the front drive shaft there was a clicking/ratcheting noise coming from within the t-case.
I've changed the fluids in the transmission and t-case within recommended intervals.
I've read about the 'Pump Rub' issue with these cases, I don't know if these issues are related to pump rub or if there is something else that may be the problem or if it's a combination of issues.
If anyone else has had experience or knowledge about this, I'd really appreciate input.
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