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As I mentioned previously, the gearing is too low, even with 10% oversized tires (LT255/85R16 vs stock LT 245/75R16). This will get worse when I put the planned LT235/85R16 tires on it, but the rolling resistance advantage of the Michelin Defender LTX will outweigh the additional 5-6% gearing loss.
Overdrive is 0.73, gears are 4.10s. RPMs are around 2100 @55, 2600 @70. With the low end torque of the diesel first/low gear on the NV4500 is useless on the street so I launch in second, unlike my old gas 350 truck.
My plan is either to stick with the NV4500 (but have it rebuilt as the 3rd gear syncro is on its way out) and convert the differentials to 3.42 (tallest stock gears) or switch the transmission to the (I’m sure very overpriced) RSG Tranzilla TR 6060 4x4 with it’s 0.5 double overdrive.
With the 235/85R16 tires, my RPMs for the various scenarios are as follows:
OD__Diff_Net _RPM 55_RPM 70
0.73 4.11 3.00 2213 2739
0.73 3.42 2.50 1841 2280
0.50 4.10 2.05 1512 1872
0.50 3.42 1.71 1261 1561
I think the 0.50 overdrive with the 4.10 gears is probably the best option, but I will have to see on price for that transmission. ( I could make it myself, it’s just a Corvette tranny with a SSR output shaft and a custom adapter plate.)
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