Not sure about the thickness, I remember reading a 8x4 tank being 1 inch thick glass, not sure the safety factor on that though.
If the outside dimentions are 96x30x48 then the insides are 94x28x47 (I think) with 1" glass
Here's what a online calculator came up with:
Water Type..............................Freshwater
Material................................Glass
Tank Overhead Shape.....................Rectangular
Length..................................94.00 in.
Width...................................28.00 in.
Height..................................47.00 in.
Wall-thickness..........................1.00 in.
Volume..................................535.52 gal (US)
Tank Material Weight....................1365.38 lbf
Water Volume............................528.45 gal (US)
Water Weight............................4397.35 lbf
Here's the calculator I used:
http://boonedocks.net/fishtank/ftweb.php