Daf XF gearbox problems?

Only had experience of scania gearboxes but there are two rules of thumb

Which could go for any gearbox

If the gearbox jumps out when its under load(foot down on throttle)
Then it could be the Syncro teeth (gearbox strip out)

If the gearbox jumps out on the over run (coasting)
Then it could be the Detent springs which hold the gear when no load applied

The linkage could also be at fault if it is adjusted wrong then the cab movement could move the stick into neutral but when this happens you would usually find it hard to get a a certain gear as the stick hits the cab,

The splitter one sounds like sonething is worn internally causing it to slip between splits

I’m afraid both sound like it is going to get expensive, Should have kept the scania, Why replace something that is not broke?

Hope this is of some help?