So the GG1 needs a Legacy upgrade for the base to version 1.6 and Cab2 to version 1.61. The Lionel instructions not really intuitive to a non-electrical engineer. So here goes:
So I dont have a Serial port on my new computer but a whole lot of USB ports. So to do the upgrade to 1.6 you need, a PC, the Legacy base unit, the cab, the Black re-writable module AND a USB to Serial cable. The Serial side of the cable had two side-screw holdowns that needed some surgery with a Dremel and cutter disc to be able to fit into the Legacy Base.
Next download the Service Module from Lionel's Website and the upgrades 1.6 for the base and 1.61 for the CAB2. Now plug in the Serial side of the cable to the Legacy base and the USB side into any PC USB port.
Open the Lionel Service Utility program you downloaded earlier, and see that at the bottom Com Port shows Disabled; SO set the Configure Connections ( by pressing the button at top) set the Serial Port AND set the Serial Port to Com3.
Note that at the bottom of the Service Utility Program the last line reads Com Port: COM 3 Open; Base should show Base: Detected. If not, check connections and redo the above steps.
IF OK then Press "Make CAB Module" on the Service Utility screen; click on previously downloaded CAB2-v161.cab2; then the Progress bar shows download progress; wait until it reads 100%; Turn off CAB2; insert Black module into the back of CAB2; next press SET and CTC and hold both until the blinking lights stop and the Opening Page is shown that CAB2 is now using version1.61.
Next upgrade the Base; remove the Black Module from the CAB2 unplug the power from the BASE; insert the Black Module into the back of the Base again and plug the power back into the Base again.
In the Service Utility screen press the "Make Base Module" button. Click on the file BAS2-v160.bas2 so the utility can read the Base 1.6 upgrade. Again see the Progress bar shows download progress; wait until it reads 100%; Now the Black Module has the upgrade for the base.
Remove the Black Module from the BASE, again unplug the power from the BASE; re-insert the Black Module into the back of the Base again and hold down the Channel Select button under the Base unit; then plug the power back into the Base again. Keep holding the button down until the lights on the Base stop flashing. Remove the Black Module and rub your finger to get back the circulation.
Take the CAB2 press CTC and the Opening Page should show that the CAB2 is upgraded to version 1.61 and the Base is upgraded to version 1.6.
Remove the USB cable from the PC and the serial end from the Legacy Base. Reinstall the Legacy Base on your layout as wired before.
WHEW!!