gotcha. that's about a 4% difference in speed, odometer, and fuel mileage. made a few hundred rpm difference on the highway when i first tuned my nv3500 truck after the previous owner didn't recalibrate for the new tires he mounted (also 245/75-16 to 265/75-16).

i think what might be missed in this argument is that the NV4500 (or any other transmission of the sort) 1st gear - even with the 3.21s - will still only get you to ~10 or 15mph before needing to shift, loaded or not. that's really short for a practical DD application, and the way they're synchronized, you'll have to be stopped to downshift into it... meaning you'll need to slip 2nd more from a slow roll to keep from lugging (and getting into the power enrichment mentioned above). that's why i believe your best compromise here is to keep your 3.73s because you ain't quite got the low torque to justify 3.42s with the kind of weight you move.

the squirreliness wasn't from your speedometer being off or from having the tools in the back of one vehicle vs the other; i'm pretty sure it was from having the expedition too far back on the trailer (in relation to the trailer axles). you want to center it over the axles & then pull forward a little bit more.

dirtydan's tahoe is 2wd, and the denali is 4wd (swapped from AWD). the difference is the tailhousing length. the tunnel don't need clearance if you get the OBS lid (or even with the NBS lid... it's just a LOT tighter in & out because the shift tower is taller.) gee whiz info for other 4x4 folks: it also uses the same 32spline output as the NV3500 & 4L80 and is roughly the same length, so it'll direct-swap to the stock transfer case just fine.

the only big blocks or diesels that had the NV4500 were OBS (454 & 6.5) and dodges (v10 & 5.9 cummins); never was paired to the 8.1 or duramax from the factory due to torque input ratings (not that it couldn't actually handle it, though).

so long as it's an MW3 from a GM, that 95 trans should work because it's got the synchronized 1st/reverse + internal slave + the correct lid for your body height. the hydraulics are different, though. you'll want to get the 01-02 master/line/slave... or even better is the 03-06 setup where you can do the same old F-body drill mod on the line & get better return flow when you let off the pedal.

they made plenty... it's just that people keep them when they can.
also, you'd still want to change the transmission lid to the OBS version to make your install easier.

 

It gets 18 mpg on the highway with the cruise set at 70-75 mph.. Low rpm at cruising speed and lean cruise. The 8.1 does not even have to break a sweat to move the Tahoe. The 99 Tahoe is more than 1,000 lbs lighter than anything that came with an 8.1 from the factory. Also as I mentioned before TUNE is a large part of it.

The 8.1 cargo van the dealership owned that I drove for 4 months years ago averaged 14 mpg. It was a standard wheel base with 4.10 gears. They always made their drivers keep a log of mileage driven daily and fuel pumped out of the tank on site. Loaded down 8.1 van got 14 mpg in mixed driving, whats hard to believe about a much lighter Tahoe with taller overall gearing (equivalent to 3.08 with the taller tires) getting 18 all highway.

 

99 is an OBS tahoe. Is that a 2dr Tahoe? A 2dr OBS tahoe weighs the same as a ext cab NBS pickup. Every time we read about an 8.1 it's because someone has big tires and quick gears to help it. With reasonable tires, highway gearing and a tune for it, I could see 18mpg.

 

Pics of said 99 Tahoe with 8.1 would be cool. I like 2 doors despite the “Less Whorez” ability

 

Mine is a 4 door LT. When I am over at the shop next I will take some pictures.

 

i was actually just looking at a 99 2door for sale the other day... too rusty underneath and only 2wd.

 

I've seen some of those 95 2 doors come in 2WD and a 5 speed manual. I would get one of those if it weren't for needing 10,000 lb towing capacity for my car hauler.

 

Everyone who thinks that brick with an 8.1 gets 18mpg, please let me know what drugs you are on. I really want them.

 

There was one that was pretty clean with the 5.7 and 5spd, white, AZ car for $4500 almost 10 years ago, and I didn't get it because I didn't want a third vehicle. I know those are hard to come by, and that's probably the one vehicle I shouldn't have passed on. I would pay two to three times that right now for that same thing.

 

My more aerodynamic brick with an engine 40% smaller doesn't get but 15 on a good day anymore lol