my 12/50 has spitfire 1500 engine fitted single rail gearbox non overdrive . gave it a quick first drive today gearbox noise terrible whine in every gear not sure what car the box came from., but has synchro in first gear my question is should i rebuild it? or i have a good vitesse 1600 box i can bolt in not bothered about loosing synchro on first , will it fit though , what box could be in the car now was the 13/60 synchro on first ? have no history of the work carried out prior to my purchase paul