This is for the r/c rock crawlers…I'm sharing the rear crossmember I use on my Gspeed V3 chassis builds. It will space the rails 2.75" (69.85mm) apart. Designed to use 3mm screws to bolt to the rails. Mount with the flat area up so that the recessed bottom gives clearance for your rear upper links if needed.

The vertical hole in the center is designed to thread a 4mm screw. I typically use a 4mm grub screw as a body post on bodies with drop beds (see pic). It could also be used to bolt a different body post on for other setups.

PLA+ or tough PLA seems to work well, though regular PLA works if you're not bashing hard with the truck. I use 5 or 6 perimeters, 5 or 6 top/bottom layers, and a fairly dense infill.

This crossmember will also work on the Gspeed V1C1 chassis rails, though it's not ideal (I do use it on mine). Due to the shock towers bolting on you'll likely end up using one end hole and one middle hole on each side.