This is a pair of custom Short rear narrow  suspension arms for traxxas Jato. 
Traxxas Jato short arms Drag racing
 
You obviously will need to do some tweeking since these are shorter than stock.
 
These arms fit right onto the Jato and use stock hinge pins or you can find some 3mm hinge pins that match up if you like. No grinding is needed for these arms to fit the Jato.
 
You will need the following parts to use these on the Jato: (See picture for example)
RCRENEW Jato rear camberlinks
Traxxas Bandit rear hubs part # 3752 
Traxxas 4-Tec inner diff cups Part # 8353 or #8353X ( Metal )  
Traxxas 4 tec rear cvd type axles part # 8351X 
 
Color may vary slightly-Manufacturing Material plastic