How to find out Allison model?

[Thumper Pilot]

Hi all,
Is there any way to know which Allison an '06 has in it (the 6-speed or not the 6-speed)? Is there something in the VIN that tells ya?

Thanks,

Jeff

[JohnC]

All MY '06 have the 6 speed. Also, look for the manual shift switch on the gear selector.

[Thumper Pilot]

Thanks John - 'MY' = Model Year? And yes, it does have the switch on the shifter. :)

[Kennedy]

How about checking the selector? DM1 on teh 6 speed and tap shift.

Select M and it will show what gears are available.

All 2006 pickups were 6 speed though from what I've read...

[Thumper Pilot]

Well, that I can't do - haven't taken delivery yet! Should have it in a couple days. I just have a picture that shows the shifter and the switch is there.

The description on edmunds.com shows 4-speed auto is the standard tranny on this truck, and the 6-speed optional. The description of the truck I bought says it's a 6-speed but sometimes those kinds of details can get 'lost in translation' in advertisements, so that's what led me to ask if there was something maybe in the VIN that would tell the story for sure.

[DmaxMaverick]

......The description on edmunds.com shows 4-speed auto is the standard tranny on this truck, and the 6-speed optional. The description of the truck I bought says it's a 6-speed but sometimes those kinds of details can get 'lost in translation' in advertisements, so that's what led me to ask if there was something maybe in the VIN that would tell the story for sure.

The 4 speed is the standard equipment on all auto tranny GM trucks. With the HD's and 3500's, it is the 4L85E tranny. However, this only applies to the 6.0L gasser, which is standard on the HD and 3500. Any larger engine and all Diesels will have the Allison tranny, and 2006 began the 6 speed Allison. The VIN will only indicate the tranny type (auto/manual), not the specific tranny equipped. The RPO sticker will tell you which tranny was originally installed. The Allison is M74, but doesn't specify how many gears. It will be M/Y dependent. Unlike the engines, the tranny hasn't been changed between M/Y's.

If it is in fact a 2006, has a Diesel engine with auto tranny, it is a 6 speed. There is no other OEM option. If it has a 5 speed or is missing the Tap-Shift, it is not a 2006 (or later). Research all you like, but that's it.

[Thumper Pilot]

OK, thanks DMax. It's definitely an '06 Duramax, so looks like the tranny they mention is accurate - Sweet! :D