Help with trans/diff fluid swaps... stupid procedural/tool questions (PICS)

Before I went to the gym tonight I set my pans under the trans and diff drain plugs and let them drain for a few hours.

First off, how do I know if I have a 3550 or a T5? I know the shifter bolts are different (4 for the T5 and 6 for the 3550, but I can't see those yet).

Second, Is this the fill plug? I can see a plug on the left side of the gearbox, but I assume it's a temp gauge hookup based on it's looks. Just want confirmation before I fill it via this hole.
http://img.photobucket.com/albums/v627/cobra4b/Panoz%20GTRA/DSCF1236.jpg

On the rear... what is the proper procedure to fill? The GTS manual says to open the top hole and fill through there. But, the side hole seems like the way to go? Wouldn't I just remove the side plug then fill w/ a fluid pump until it starts to overflow? I couldn't get a rachet extension in there as the hex size is odd... anyone know what size hex rachet thingy I need to get?
http://img.photobucket.com/albums/v627/cobra4b/Panoz%20GTRA/DSCF1233.jpg

Thanks... just want to get it right the first time around :screwy:

The plug in the tranny is the fill plug.
On the diff, I'd pull the plug in the side and fill with oil from the top until it starts coming out the side plug. If you fill from the side plug, you have to stop filling periodically to see if your full. If you fill from the top, you don't have that problem. The hex wrench is a 3/8". Just confirmed in my diff.

^ Jerry... on the vette the trans and diff fills are "fill until it overflows" so that's no biggie... just pump the hand pump until you know you're reaching the specified amount then slow down. Let any excess drain, clean up, then install plugs.