Thanks Chris, MOgolf, and onehotspud for your input
Chris, couldn't we determine whether it's an IMMO-II cluster by just looking at the T20a connector on the back? From what someone else told me, the T20a red plug is used up to april of 2001 and T32a green is from may 2001 and on (cluster build dates; I'm assuming the IMMO-III cluster didn't have the T20a connection on the back since they did away with it). If this is the case and it is an IMMO-II, I'm in luck because then I can use the 3LB cable and get the arrows to show up from my MFD navi without the need of a TMC box.
Now my only question is whether I can use a MFD-G with this setup or if I specifically need a MFD-D since it uses 3LB. I haven't figured this out on my own yet because I'm in Europe until the end of the month. I will be picking up the T20a connector and cable when I'm in Germany in a few days.
EDIT: One more thing, are the screens / appearance of the icons, ect. any different on the IMMO-II FIS compared to the IMMO-III FIS?