Hello all! I have created a nice blog post regarding Allison Transmissions. This includes:
1) How to tell which generation model you have
2) How to clear/troubleshoot codes
3) Free service & troubleshooting manuals
4) How to reset the oil and/or filter lights ("TRAN SERV" light that comes on)
... and a bunch more.
You can find the post here: 99-Allison-Transmission-Resource-Guide