If you have a spare dogbone, cutting a solid aluminium one shouldnt be too much of an issue...as for aluminium inserts for the others, you might as well make them all solid, or go with the prothanes
Hell, if you make them all solid, you can relocate the center hole lower in the opening and drop the center of gravity down a bit and ease the stress on the axles for lowered cars. Although, this wouldnt bode well for the oil pan
