The TT01 and the TT01D is the same chassis.
The 01D just comes with extras that the 01 doesnt come with ie:
oil shocks, bearings, sport tuned motor, adjustable upper a-arms for camber settings and a few other upgraded parts.
For wider bumper you could just get a piece high density foam and shap it to suit the body you are using.
casterracing EX-1 Pro, SP Silver Arrow
TOP Racing Scythe, SP 17.5, SP GT Pro 2.0
TOP Racing Scythe, SP 4.5 V2, Hobbywing Xerun 120SD 2.0
TOP Racing Scythe, SP 13.5, Hobbywing Xerun 120SD 2.0