[buzzinhalfdozen]

Not familiar with this particular trans , however I'll assume it has a detent system for the shift rails? If so is it possible for some reason rail is not moving enough for detent to sit in rail groove? That is what basically holds it in gear along with any back cut on the shift sleeve. Take the linkage off and by hand move the shift arm you should be able to feel the detent drop into the shift shaft rail. Joe