The 8ight RTR doesn't have the fancier machined aluminium shock towers, hinge pin braces etc that the 8ight race kits have. Though that is about it really. The 8 E is an 8ight 2.0 with Losi's conversion kit, and electronics bundled, which saves money over buying them separately.
Converting an 8ight buggy to an 8ight T would be pointless, and expensive, as the parts shared (more or less) are:
Front + Rear Gearboxes, braces etc
Steering rack + brace
Centre Diff Mount, and diff (and possibly the Spur?)
Radio Tray
Rear wing mount
Steering Knuckles, C-Hubs and rear Hubs.
To fully convert, you would need new:
Chassis + Side Guards
Suspension Arms (upper + lower)
Turnbuckles (all of them)
Wheels + Tyres (obviously)
Shock Towers
Body Mounts + body
Whoaah, almost said Fuel Tank! Urrrgh!
Driveshafts all round
And the list goes on (as do I

)
You can probably pick up new 8T 1.0 rollers on eBay, or at shops, pretty cheap now, as the 8T 2.0 has come out.