Thank you to all for your replies! Fortunately, the gearbox is not damaged internally! We discovered the problem thanks to some detective work from both our mechanic and from forum viewers like you! The inner rubber boot for the shift linkage is the culprit. It is no longer supple and as such occasi...

We have a 1971 Lancia Fulvia with a 818.630 gearbox that jumps out of fourth gear. We would like to get the box rebuilt, but are having trouble finding someone here in the States that can do it in a timely fashion and without spending a fortune. Do you have any ideas as to US or international gearbo...