For some reason 5 speed boxes with double synchro (98on) often break the ring between both synchros on third gear when second breaks. They sometimes break the 5th gear hub as a result too. It seems unrelated but it happens regularly. The third gear synchro assembly actually costs more than the driven side of second gear.
Budget on minimum $1800 by the time you renew all the busted bits and a few seals and gaskets, oil and Labour.