At about 60 MPH level surface, tires 265/60R/18, I’m seeing around 2100-2200 rpm. As I’ve never been in an actual Discovery before I drove this one I have no idea if that’s in the “normal” range. It seems to shift through all 4 gears and doesn’t seems to be slipping.

I do hear a very almost imperceptible whine from the trans that I’m assuming is coming from the trans as it coincides and changes pitch with the shift points.

Im still shaking out things and the vehicle runs strong but having nothing to compare it to I’m constantly on alert for “is that a normal noise, or a bad $$ noise”

 

RPM sounds normal. Whine is probably transfer case not tranny. Have you checked the oil level in the transfer case?

 

Yeah I checked and topped off all fluids including the Tcase

 

I’m running 4.47 gears, 305/65/18
my highway rpm is 25-2700 @ 70mph
Engine runs at 194

 

Just for reference, your tires are about 1.5" taller than what came stock on your vehicle, so you're probably going over 60mph when the speedometer in indicating 60. You might want to check your true speed with a gps or smart phone.

 

I have an 03 on 265/75/16

2050 RPMs at 60mph via GPS
2150 RPMs at 60mph via the speedo

 

Ok that tracks with what I’m seeing. Should have stated clocking 60 from GPS not speedometer. The whine is most likely from the transmission. It follows the shift points and goes away if I shift in neutral. I’m assuming the Tcase would still whine if it were the source and the transmission was in neutral?

 

Do not assume that. Torque from the transmission is applying force to the transfer case in a way that does not match the torque being applied when rolling in neutral. Because of that, the source of the sound is likely under different conditions and would react differently, to mean it may not make noise under all conditions.

 

How would I check to see if the torque converter goes into “lock up” at highway speeds. Ultra gauge has me at 12.8-13 MPG not heavily loaded rig. What I’ve read should be getting better gas Milage than that. Not sure if the ultra gauge is accurate with the slightly lager tires. Vehicle rpms seem like there should be another “overdrive” gear at highway speeds

 

The Ultragauge has no accurate way to actually tell MPG. You have to do that the old fashioned way with math. Since you already know your speeds are off, don't forget that means your odometer is off too. I have found that the Ultragauge is not accurate for speed either. Use the GPS for MPH and for actual miles driven to do the math accurately. Doing the math this way I get around 16.5 highway at 70mph. I would love an overdrive for highway driving!!!