Totally frustrates with trying to figure out what to do with the ProStar recommended Associated rear bumper kit I purchased when I ordered the chassis, a friend sent me a picture of how his Cobra 2WD chassis (forerunner to the ProStar) was built for him. Very much different than what is shown in the ProStar website but still extremely weak and fragile appearing with only a single attachment point (two screws to the shock tower). So being a TEKNO purist, I took the rear bumper off a SCT410 and played with it to see how it would fit AND IT DID! Only required one modification and two longer screws. The holes holding the D brace on the ET410 are spaced closer together (about ½ the width of a screw) than on the SCT410, so I had to redrill those holes on the bumper to allow for this – it was more like I augured out the hole to make the gap narrower). Once this was done the bumper was a direct bolt on two longer screw into the D brace and two screws into the shock tower; and is as strong as the SCT410 bumper on a SCT410. I do recommend you disconnect the shocks and remove the wheels - it makes it easier to put the screws into the D brace without the A arms coming out and those little spacer going all over the place. Now I won't be afraid the bumper will break if a corner marshal picks the truck up by the rear bumper - its TEKNO STRONG!