Zoo Motorsport modified a beam kit & supplied shafts, however ive had to get special shafts made to cope with 660ft-lb since. Its like all things a solution you can fit/forget is worth a few extra bob & a lot less stress. JB has spent more on standard diffs at £50 a pop than my whole rear end conversion which is bullet proof. Think beam was £1700 fitted with shafts + diff £450 so around 2.2k, up to 600ft-lb its fit/forget.