Allison Transmisson Identification

[bpshunter]

i just bought a 2001 2500hd reg cab with the 8.1 in it and i was wondering how i tell if i have the allison transmission?

[Phazer_II]

The 5-speed Allison transmission is RPO code M74...look in your glove box for it.

[Superman TNT]

I don't think GM offered the 8.1 without the Ally . . .

[shocktrp]

Allison has transmission oil filter on the outside, 6L80E does not?

[Stewmeistr]

Look underneathe,............. is there a BIG@$$ transmission under there with a little tiny filter on the drivers side? Sorry for the sarcasm.. All 2001's with the 8.1L came with the Allison UNLESS you bought a Suburban/Tahoe with the 8.1.

Later,

Rob

[jhoff8487]

In addition to the RPO codes, types of filters, etc. If I recall from my Allison 1000 Series maintenance course, on the bottom of the tranny or on the pan there is a huge Allison logo stamped in the metal. It's a quick clue.

[BlackSilver]

In addition to the RPO codes, types of filters, etc. If I recall from my Allison 1000 Series maintenance course, on the bottom of the tranny or on the pan there is a huge Allison logo stamped in the metal. It's a quick clue.

 

Wanna bet there isn't some dufus after-market shop out there making Hydramatic pans with Allison logos on them so that posers can feel good about their 6.0's?

[2000DV4.8]

In addition to the RPO codes, types of filters, etc. If I recall from my Allison 1000 Series maintenance course, on the bottom of the tranny or on the pan there is a huge Allison logo stamped in the metal. It's a quick clue.

 

Wanna bet there isn't some dufus after-market shop out there making Hydramatic pans with Allison logos on them so that posers can feel good about their 6.0's?

 

 

 

 

You sonofabitch, you said you wouldn't tell anyone about that!