If you can't get hold of TT01, the TB01 could be of close resemblance, geometry wise etc. I'm not sure abt the weight though. TT01 looks more compact and less sturdier.
Apparently TT01 is evolving too...
from Tamiya/Team Orion web.
Check this one out:
53670 TT-01 Aluminum Racing Steering Set
Presenting a complete steer set for the TT-01 chassis to eliminate those little tweeks caused by using molded parts. A pre-assembled aluminum steering arm with bearings provides more sturdy steering control. Comes in blue anodized aluminum.
53671 TT-01 Front One-Way Unit
After receiving many requests from TT-01 chassis users for more optional parts, Tamiya now delivers a Front One-Way Unit for this chassis. Having some parts in common with item 53507 TB-01 Reinforced Front One-Way Unit, this item will give smooth running to your model.
53672 TT-01 Carbon Upper Frame
In order to give an improved strength to the TT-01 chassis, Tamiya offers a Carbon Upper Frame.