My box went bang too and shite did it make me jump, was giving it some welly in 2nd up a hill and snapped the leyshaft, wasn't long after i had the new engine in so i cant see yours lasting Paul
Got mine done by a company near me, wasn't too pricey and its been totally sweet since, not that im expecting it to last much longer, but im careful not to boot it up hills or with 4 people in cos i know it may go again.