2002 Chevy Allison swap need help please.

[Roddy68]

My 02 Allison is down. After replacing many new parts with no good results, my question is really can I swap my 02 ally with an 05 that I found with 60 k on it. mine has 175 on it. From what I found so far is fluid line connectors change and nsbu switch, will I need to change out valve body’s? Thanking you guys in advance for any help with this.

[DmaxMaverick]

2003 got a complete electrical and calibration makeover, so not likely a simple fit. I recall a discussion on the 6-speed upgrade, and this was an issue (01/02 were not candidates). Maybe a question for Kennedy?

[Roddy68]

Thanks for the reply. I read on another thread tha someone was swapping out an 05 ally with an 02 and he needed to change coolant quick connections,nsbu switch, and his valve body, with harness from his 05 and it would work. I just wondered if could be done like that only from 02 to 05. So your thinking with the 05 still being a 5 speed, the calibration diff wouldn’t allow it to work?

[DmaxMaverick]

The 6-speed upgrade I was referring is enabling the (pre-existing) OD2 in the 03-05 Allison with minor hardware and a software calibration. The 2001 was definitely not an option, but inconclusive on the 2002, and I've not heard of a successful 2002. I had seriously considered doing it myself, but the updates required would put me in an entirely different emission class of headaches (a CA thing). The 2001 CA smog equipment is the same as federal trucks (essentially none, except for the glow plug harness and controller, and calibration differences), but changed for 2002 (EGR and cat added for CA smog). This may contribute to the absence of successful 2002 6-speed upgrades in CA. If the valve body swap is required on yours, and it works, perhaps look into the 6-speed option at the same time. If it is an option, and you're already doing it, the upgrade may be worth it. I suggested contacting Kennedy, or someone else who's actually had a hand in it, to shoot it straight to you. No need to guess when the answer is available.