The Y-piece is machined from a solid block of 6061-T6 aluminum, then de-burred in a media tumbler.  The front engine mount is machined into the Y-piece such that you will not have to fabricate front engine mounts. The ends are machined to fit over the tubing of the frame to allow the strongest welds.  With this Y-piece, you do not have to replace the square tubes that run under the engine. As you can see from the images it makes a very clean looking conversion.  CR500 engines from 1985 to 1988 can also be used, but require the swing-arm bolt bushings in the rear of the case to be modified.