here is a pix of the way I am going to plumb my heater. This is not my tractor, seen it at a show and took the pix. My tractor has the new style injector lines and pump so the middle hole is not axcessible. but the plug right behind the alternator is, thats the one Im using. and will be very neat looking. I use the hole in the other side of the block center for the bottom of the heater. Hope this helps.