this is from a dealer posting. I have some scant info that it is indeed correct. Apparently the 3LT-Lt option code is the old 1SB.
The big deal to me is MXO...apparently now 6 speed. I see no G90 option for the 3.15 axle. For what it is worth I captured the following...

1YY07 - Corvette: Coupe
Options:
10U-Arctic White, Exterior
19U-LeMans Blue Metallic, Exterior
41U-Black, Exterior
45U-Velocity Yellow
67U-Machine Silver Metallic, Exterior
71U-Daytona Sunset Orange Metallic
74U-Victory Red, Exterior
80U-Monterey Red, Exterior
023-Cobalt Red Leather
193-Ebony Leather
313-Cashmere Leather
843-Titanium Leather
1LT-LT Package Option 1
2LT-LT Package Option 2
3LT-LT Package Option 3
C2L-Roof Package, Dual Removable
CC3-Roof Panel, Removable, Transparent
F55-Magnetic Selective Ride Control
FE9-Federal Emissions
LS2-Engine, 6L, LS2, V8 SFI
MN6-Transmission, 6-Speed, Manual
MX0-Transmission, 6-Speed Auto
NE1-MA/ME/NY/VT Emissions
QG6-Wheels, Painted Aluminum
QG7-Wheels, Polished Aluminum
R8C-Corvette Museum Delivery
U2K-XM Satellite Radio
U3U-Sound System w/Navigation
UE1-OnStar System
US8-Sound System
US9-Sound System
VK3-License Plate Bracket, Front
YF5-California Emissions
Z51-Performance Package

|UPDATED|3/14/2005 7:25:18 PM (AZT)|/UPDATED|

Good info, thanks for sharing.

Yes, there will be a 6 speed automatic available, replacing the 4 speed auto.

Yes, thanks for the info. That is the transmission I
have been waiting for. It was only a matter of time.
Mileage will be so good we will have to stop and empty
some fuel out on a long trip!

I found some specs on the STS-V Hydra-Matic 6L80. It has a listed 430 lb-ft of torque capacity versus the current C6 4L65E of 380. The six speed in the caddy has a 258 mm torque converter versus 300 mm in the 4L65E. The fact that it has a torque converter says that GM went cheap versus the Audi twin countershaft model. The gear ratios of the 6 speed versus the (4 speed) are listed below. The lower gear ratio for the 6 speed first gear suggest to me that the G90 axle (3.15) probably won't be offered for 2006, which is consistent with the option list I published above.

1st gear 4.02 (3.06)
2nd gear 2.36 (1.63)
3rd gear 1.53 (1.00)
4th gear 1.15 (0.7)
5th gear 0.85 --
6th gear 0.67 --
reverse 3.06 (2.29)

this is from a GM Powertrain posting...

GM Powertrain introduced its first 6-speed automatic in the 2001 Buick Bengal concept car.
Several 6-speed variants will be featured in GM vehicles worldwide.
The first 6-speed will debut in 2005 (applications to be announced at a later date)
New Technologies:

Clutch-to-clutch (the actual Caddy trans above has this for all shifts except the 1-2 shift which they call "freewheel shift".
Controls characterization
TEHCM – Transmission Electro/Hydraulic Controls Module
Shift-by-wire (ETRS)
Features:

Neutral idle
Automatic grade braking
Driver Shift Control (DSC)
Enhanced Performance Algorithm Shifting (PAS II)
Next-generation tow/haul mode
Benefits:

Fuel economy
Performance
Premium shift quality and driveability
nullnull

I was about to order my C6 Monday but read about the new 6spped auto replacing the 4 spd. Any idea how soon this new tranny will become available?
THANKS !!!

Dealers can not order 2006 Corvettes until late June. The tranny will only be in the 2006 model year and that production doesn't start till September 9th.

In the continuing slow leak of 2006 information it seems that the 6 speed auto will come with a 2.56 gear rather than the current 2.73 (?) and the optional 3.15. Thus it appears that GM is going for higher gas mileage numbers.

Also, the 3LT option package replaces the 1SB and includes the XM radio. It does not include OnStar is spite of Chevy announcing that it would soon be standard in most of their cars.

|UPDATED|3/14/2005 7:27:18 PM (AZT)|/UPDATED|

Apparently that initial post of mine from a Chevy dealer post is not worth much. That dealer has now said that there will be no 6 speed automatic for the 2006 model year. I have waited years for this tranny. It has been announced for that Caddy. Probably the politest thing for me to say is that I am crestfallen. A long time ago I read "All Corvettes Are Red". It detailed the on and off of GM when money was tight for development of the C5. I have to wonder if the Fiat negotiation hasn't dried up all the money again.

I have read posts of others that claim that the 6 speed automatic will not be available at the beginning of the 2006 production (Sept 9, 2005)but will make it later in the year. I am pinning my hopes on that and told the dealer where I have my deposit for his first allocation that it should go to someone else. I sure wish it were June.