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first year allison offered?

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I'm completely new here. Don't even own a truck yet! [Please don't throw me out!] I'm studying them prior to buying my first one, to become my first travel trailer tow vehicle. I've decided I really like the Silverado 2500HD but there's no way I can make the numbers work for a new one, so I'm using the Internet to shop for a "good used" one. Preferably 2002 or newer.


As for engine, I've decided that to tow the trailer I'll probably buy I'll be much better off with the 8.1L engine than the 6.0 or smaller. And I think a diesel, much as I'd like one, would be overkill for me right now.


So here's my question: I just browsed the RPO codes for 2002, 2003, and 2004. I know I want the Allison tranny, but I was surprised that I couldn't find the RPO code for it, explicitly, in the 2002 list. In the 2003 and 2004 lists I can find M74, Transmision, Allison 1000 5-speed automatic. But I don't find the word Allison explicitly in any of the 2002 codes.


Is this a way of saying that GM didn't begin offering the Allison 1000 5-speed automatic AT ALL till 2003?


If so, that'd mean I should stop looking for used 2002s, which is the real point of my question.


Thx, and again, please don't flame a newbie! We all gotta start somewhere!



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I thought the first year for the Allison was 2001.







Yep, First year for the the Allison in light duty trucks was 2001 which was also the first year for the HD trucks. :cheers:






Yes, I just bought an '01 C2500HD extended cab long bed yesterday, with the 8.1/Allison/3.73.

The RPO for the engine is L18, the Allison is M74, and rear axle ratio 3.73 is GT4.

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