The reason for the difference is the way Toyota's, including Lexus are distributed in the Southeast Market. This is from Wiki but is accurate.....Southeast Toyota Distributors, LLC (SET) is the world’s largest franchised distributor of Toyota vehicles. The 172 dealers in the five states of Florida, Georgia, Alabama, North Carolina & South Carolina account for 20% of Toyota sales in the United States. SET is a wholly owned subsidiary of JM Family Enterprises.(end)LC4LIFE,
I had something similar happened with mine. For some reason the LCs comings from the south-east will have a different system (according to the Toyota dealership). I could never trace mine to the south-east, but it was a weird case for sure.
I have a Florida LC with the Audiovox aps-400 TDS installed. I have the same ELVAT5G remote.. and found the main module 00016-30965-01 tucked up behind the main fuse box above drivers left foot. My FOBs died, and in exasperation I simply removed the main module .. problem solved, I can start the truck again. Am considering removing the entire TDS assembly, selling it, and getting a simple door lock remote.
Here is the manual for the system, I haven't seen it online.. hopefully it will be helpful to others.
Audiofox APS-400 manual 1994 - Google Drive
Included above are pictures of the main module and my key FOBs.