Perfect solution for someone that doesn't have access to a welding machine. Provided in the kit is a template that allows perfect alignment for the bolt holes and exhaust cut out - through the factory crossmember. The template utilizes an existing hole in the cross member to locate the template, insert one of the supplied bolts, clamp in place and mark the remaining holes for drilling. A step bit can be used to drill the 5/8 holes.(Not included). For the larger hole in the center, the hole in the template is larger to allow a plasma torch to be used as a guide, but if you don't have a plasma torch other means can still be used to cut the hole. Also provided is all the grade 8 fasteners required to install the exhaust cut-out. This installation is a perfect option if you don't want to remove the cross member and still be able to tuck the exhaust up inside the frame. Inside dimension of the pipe is 3-1/2. Fits rear wheel drive trucks with trailing arms and coil spring rear suspension.