6.6 Gas L8T Engine Swap in 2015 Suburban

the 4l60 ratio spread reminds me why I never want to regularly drive anything with 3 gears + OD (or worse, just 3 gears and no OD like the THM400 in my ‘77 GMC 3/4 ton camper special pickup with a 454) again!

Years ago I bought my wife a 2008 Saab 9-7x Aero (occasionally known as the ‘Trollblazer’) with a LS2 + 4l65e and again the transmission was easily the worst part of the entire experience. That truck sounded great but drove in the same underwhelming way of all GMT360s, and would have benefitted from a 6l80 or 90 but I’m sure old GM wasn’t doing any driveline development work on badge-engineered TBSS stuff at that point (although the interior was substantially better than a TBSS although again that’s not saying much.)

10L80: ... 4.69 ... 2.99 ... 2.15 ... 1.77 ... 1.52 ... 1.28 ... 1.000 ... 0.85 ... 0.69 ... 0.64 (MF6 in suvs)
8L90E: ... 4.56 ... 2.97 ... 2.08 ... 1.69 . . . . . . . . 1.27 ... 1.000 ... 0.85 . . . . . . . 0.65 (M5U)
6L90E: . . . . 4.03 . . . . 2.36 . . . . . . . . . 1.53 . . . . . 1.15 . . . . . . 0.85 . . . . . . 0.67 (MYD)
4L70E: . . . . . . . 3.06 . . . . . . . . . 1.63 . . . . . . . . . . . . . 1.000 . . . . . . . . 0.69 (M70)
4L85E: . . . . . . . . . . . 2.48 . . . . . . . . . . . . 1.48 . . . . . . 1.000 . . . . . 0.75 (MN8)

(Once GM determined that the GMT360 / GMT370 were taking big bites out of Tahoe sales,
that's when the GMT360 / GMT370's demise became guaranteed.)

Marky Dissod said:

10L80: ... 4.69 ... 2.99 ... 2.15 ... 1.77 ... 1.52 ... 1.28 ... 1.000 ... 0.85 ... 0.69 ... 0.64
8L90E: ... 4.56 ... 2.97 ... 2.08 ... 1.69 . . . . . . . . 1.27 ... 1.000 ... 0.85 . . . . . . . 0.65
6L90E: . . . . 4.03 . . . . 2.36 . . . . . . . . . 1.53 . . . . . 1.15 . . . . . . 0.85 . . . . . . 0.67
4L60E: . . . . . . . 3.06 . . . . . . . . . 1.63 . . . . . . . . . . . . . 1.000 . . . . . . . . 0.69
4L80E: . . . . . . . . . . . 2.48 . . . . . . . . . . . . 1.48 . . . . . . 1.000 . . . . . 0.75

(Once GM determined that the GMT360 / GMT370 were taking big bites out of Tahoe sales,
that's when the GMT360 / GMT370's demise became guaranteed.)

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That and the bankruptcy...

I am considering the thought of selling. Anybody interested in this thing? 193k miles as it sits. Daily driven. Clean, clear Kentucky title. Own one of the VERY few 6.6 swapped Suburbans! Only around 10k miles on the 6.6 L8T w/6L90 combo. This thing hauls! My mind isn't completely made up, but just gauging interest at the moment.

I have a HUGE list of upgrades. Far too many to list here. This is the closest to a fully bulletproof setup that you can get in this platform with the engine and transmission setup.

Shoot me a message if truly interested and i can give more details and pictures.

L8T BURB said:

I am considering the thought of selling. Anybody interested in this thing? 193k miles as it sits. Daily driven. Clean, clear Kentucky title. Own one of the VERY few 6.6 swapped Suburbans! Only around 10k miles on the 6.6 L8T w/6L90 combo. This thing hauls! My mind isn't completely made up, but just gauging interest at the moment.

I have a HUGE list of upgrades. Far too many to list here. This is the closest to a fully bulletproof setup that you can get in this platform with the engine and transmission setup.

Shoot me a message if truly interested and i can give more details and pictures.

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I wish I had the $$. Awesome ride.

L8T BURB said:

I am considering the thought of selling. Anybody interested in this thing? 193k miles as it sits. Daily driven. Clean, clear Kentucky title.
Own one of the VERY few 6.6 swapped Suburbans! Only around 10k miles on the 6.6L L8T w/6L90. This thing hauls!
My mind isn't completely made up, but just gauging interest at the moment.

I have a HUGE list of upgrades. Far too many to list here.
This is the closest to a fully bulletproof setup that you can get in this platform with the engine and transmission setup.

Shoot me a message if truly interested and i can give more details and pictures.

Click to expand...

If you rush to sell, you will lose LOTS of money.
Patience will find you a buyer who truly appreciates what you've done.

Marky Dissod said:

If you rush to sell, you will lose LOTS of money.
Patience will find you a buyer who truly appreciates what you've done.

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Yes sir. I planned to make this a long process to hopefully bring in the right buyer. Having no lien on the vehicle allows me to wait this thing out without getting frustrated that I'm still making payments on it lol!

What axle gear? (Forgot.)

A niche buyer will pay for it, a regular car shopper is most likely scared off by the numerous modifications. Need to be very mechanically inclined, the average shop would probably mangle a repair on that rig.

Marky Dissod said:

What axle gear? (Forgot.)

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It is the standard gearing, I believe 3.08.