chris21

I'm pretty sure it doesn't actually recalibrate the speedometer it just changes the wheel speed sensor inputs to the computer. The truck still thinks it has stock tires.

37's would probably fit with a 3" lift. GM only has two gear ratios for these trucks 3.73 for gas and 3.42 for diesel. And they can't be programmed for anything else at the moment. The rough country module just corrects the speedometer and odometer to adjust for tire size it's not a programming device. You haven't said if your truck is gas or diesel, but for a gas truck the 10L1000 with 3.73 gears has a lower final drive ratio than the 6L90 it replaced would if it were swapped to 4.10s. GM used the same 3.73 gearing in 6 speed gas trucks. I don't think you'll have any issue running 37's with the 10 speed other than the reduction in mpg and towing/weight capacity which is as much of a function of the lift as the tire size.

I didn't mean to seem dismissive of hurting mpg. Lifting the truck while still using stock tires would hurt mpg too, I was just saying that both engines have plenty of low end combined with a low first gear that drivability would be fine with stock gears. Towing with a significant lift sucks regardless of engine, transmission and gear ratios. And suspensions that allow extra travel don't carry extra weight well. If you're using the truck to tow or haul near capacity a big lift isn't great and reduces the the truck's capacity and these trucks are too heavy and long to be good for serious off road.

37's are within 10% of stock. The 10 speed has a really low 1st gear. Neither engine will really struggle. There is only one device currently that can trick the computer to correct for tire size, there are no programmers that work on the global B trucks that I am aware of, so programming the transmission shift points for re-gearing isn't possible at this time that is why there are no parts available for it.

Top yours off when you want. That is your decision. Different engines can have different markings and recomendations. The LT1 in my boat for instance the dipstick has 8 oz. Markings for a 1.5 qt range(7 dimples 1/4" apart) and 5qt sump it uses 20w-50 race oil and I keep it between the top two marks and change the oil every season or 50 running hrs. My truck has the 1 liter crosshatch and it depends on how soon I am going to be changing the oil how far down the crosshatch I would let it get before adding some. I haven't needed to add oil to my current truck as I haven't seen it below the top quarter of the crosshatch within 4000 mile oil changes. I had a 2002 5.3l that I added a full quart to every 2000-2500 miles that I drove until I sold it with 275,000 miles on it and a 4.8l that I never had to add oil to between changes that I drove until it had 300,000 miles. Every engine and use case is different. I'm sorry the owners manual is somewhat ambiguous I didn't write it.

You seem to be struggling with reading comprehension. I HAVE SAID 3 TIMES THAT THE BOTTOM OF THE CROSSHATCH IS A QUART OR LITER BELOW FULL. I have also said that the manual will not call that "1 quart low" because it is not a quart below the acceptable range in answer to asilverblazer saying that he has never seen the bottom of the marking noted as "1 quart low" in a manual. The wording of the manual allowing for an acceptable range would indicate that .00001" above the add mark is ok. Also, because the manual allows a range, a quart below full and a quart below acceptable are two different volumes. Thus the manual will not use the phrasing "1 quart low"

Note my quotes around "a quart low" adding 1 oz when at the bottom of the crosshatch/acceptable range would bring it back to within the acceptable range therefore it would not be considered a quart low according to what the manual calls the acceptable range even though you can add a quart and not be over filling at that point. I was explaining why the manual would not say the bottom of the crosshatch is a quart low.

The bottom of the crosshatch wouldn't be "1 quart low" in the published manual because the range of the crosshatch is the allowable range. The crosshatch is approx. 1 quart or liter so that when the oil level is at the bottom of or below the acceptable range you can safely add 1 quart or liter without overfilling.

Here is the manual for my 2025 it does infer that the crosshatch area should be appox 1L. and it says the oil level should be checked cold and parked on level ground. Also to check every 400miles.

That screw is just holding the tail light in. There should be some play in where the screw can be tightened to align the taillight.

The most common issues with the 7.3 Ford are more catastrophic than the common issues with the GM 6.6 gasser. There is very little actual data on frequency, but there are certainly more compaints of engine failure due to cam, lifter or oil pump failure on the Ford 7.3 than the GM 6.6.

Intake leaks can make a whistling sound as they change the flow of air in the intake.

Not sure about the current DI motors, but with the previous generations of 5.3 and 6.0 an intake leak would be audible long before it threw any codes.

And crickets... @James McArthur a few of us had questions of genuine curiosity. The pictures you shared showed dark colored oil and dirt/dust? residue on the mating surfaces of the head where the intake manifold was attached. Those mating surfaces should be clean.

You never did share how frequently you had the oil changed in this engine? I am also curious if the air filter was ever changed or if you used an aftermarket intake?

It will only go full blast/max cool on auto if you turn the temp down to LO.

2 decades ago first oil change at 1000 miles then 3000 mile OCI was an almost across the board manufacturer recommendation. Edit to add... Also most manufacturers specified 10w-30 in warm climate and 5w-30 in cold. And higher viscosity for hd use. Not the 0 weight oil they call for now.

If you're under 5'10" you might need a ladder just to see the oil filler tube

Interesting, my 2500 double cab gasser has a higher GCWR by 2000lbs, and tow ratings by 2300lbs for each conventional and gooseneck with higher tongue weights(10% and 15% of trailer weights). And the max payload is only 300lbs lower.

The rough country inline is the only one that claims to work with Global B gm trucks. It doesn't change shift points for the transmission though. Your speedometer and odometer are probably reading 2-3% high on the stock calibration if you have 275/70/18's now, but that is only 1-1.5 mph at 50

That tire change will most likely make the current calibration of your speedometer and odometer accurate.

This also probably means your right turn signal doesn't flash on the trailer

Sounds like connector on the truck is not wired correctly

Check the ground on the trailer

Did you ever find the source of the chirp under light acceleration? I am having a similar sound in my 2025 2500 with 3000 miles, with light acceleration between 30-40 mph and only when the engine has a little bit of load. I thought it was coming from the rear end, dealer said they didn't hear it, then after a second drive they said it was my truck cap whistling... but it is a chirp that clearly only happens under light engine load. I added fluid to the rear diff as it was a bit over half a quart low (same dealer said level was fine, took over a half quart to bring it up to 1/2" below the fill threads) it still made the noise after that.