are there any diff conversions for the old girl that bolt in that has taller gears and maybe has limited slip.it has a tired 18r engine and column shift but grip factor is zero in wet.i know its light in the back but this is ridiculous.it has new tires and i,m worried if i drive on damp worksite it will bog too easy.i need taller gears cause its near screaming at 90 kph.thanks for any info people. ps.also need info on changing existing drums to disk brakes.