My auto transmission in my 456M GTA slipped into "limp mode" after a few days of blinking warning lights (SDL, CEL and ASB). A rebuild of the transmission and torque converter was recommended and done. After reinstalling the rebuilt drivetrain, the same blinking warning lights remain although the tranny shifts and runs fine. Previous posts say that a reprogramming of the TCU and/or ECUs is needed to clear the warning lights. If so, who can do this? ECU Doctors in Florida? Can either module be "reset" and if so how? Your input is appreciated.

What do you mean by "limp mode"?
Specifically, is the engine running on just one bank and (now) the transaxle is shifting correctly?

Generally speaking, a "slow-down" light coupled with a "check engine light" is indicative of a problem. The ABS warning is a different, likely unrelated animal. Regardless, you really need someone local to pull engine codes. To pull any code or diagnostic data out of the transaxle will require a factory SD tool.

Keep in mind that resetting faults and correcting the problem (I'm presuming that there is) are very different issues.

I believe the transmission rebuild has solved the mechanical problem but the warning lights remaining suggest to me that the TCU needs reflashing. Can the TCU be reset (flashed, reprogrammed, etc.) or are the previous faults "permanently" set? Can you also explain to me the communication line between the two (2) bank ECUs, the two(2) cat ECUs and the single (1) TCU? Which control unit is responsible for triggering the SDL? the CEL? Your help is appreciated.

Please post two pictures of your dash; one with the key on, the other with the engine running.
Is the car running on both banks or just six cylinders?

Frankly, you need a local resource with a factory SD-2 diagnostic computer....It will make this/these problem/s much easier to find and correct.

The two engine management units are 99% independent of one another. There are two ECUs, one for each bank. Both have a crank trigger. One bank has a cam phase sensor which detects TDCC, with some assistance from the crank trigger. There are two thermo-couples (TC) which measure exhaust temperatures. These units "report" to cat temperature monitoring devices (often called a slow down ECU- SDECU). When high cat temperatures, open circuit conditions or illogical voltages/temperatures are reported, the ECU for the particular bank in question will be shut down (no fuel). You will see both a Check Engine light and a Slow Down light.