Gearbox shudder/vibration at idle in gear

Anyone care to offer advice on this please? '95 Hiace 3L 2.8d auto camper.

From cold the auto box operates perfectly. Once warmed up, at a standstill there is a pretty serious shudder/vibration through the gearbox when in D or R with foot on the brake.. It goes when either I touch the accelerator and take the revs up a touch, or pull away and get on the move. No issues when in park or neutral, and no issues changing up or down whilst in the move, it's very smooth and doesn't lurch or shudder at all.

I have just changed the ATF, the old stuff that came out looked pretty clean (red), so I'm fairly sure the transmission is in good order.

Is it something that could be adjusted in order to bring the revs up slightly to counter the shudder as it is at present, or could there be a bigger problem that I would be masking by doing this (If it is possible) Any further tune ups/adjustments that can be done on these boxes?

Or are there any other suggestions? Are worn mounts common on these, and if so could this cause the problem? Or is there anything like a vac leak that could be causing it?

The only other issue I've got which I'm wondering may be related is when braking (always smoothly with plenty of allowance for distances etc) there seems to be a vibration/pulsing feeling coming through the pedal. This doesn't feel like warped discs, I've driven plenty of cars like that. I've not got round to checking the rear shoes yet.

Any thoughts greatly appreciated. Other than that she's a lovely old bus

What RPM does it tick over at?

I haven't checked it yet Clive, but I would say 7-800 rpms out of gear? I have no rev counter but will get a gun on it later in the week to confirm. What's your thoughts?

Perhaps just a little upping of the tick over will cure it?

I'll give that a go first certainly, i'll report back with my findings! Cheers Clive

Ok, idle upped and no improvement unfortunately. I've taken a short YouTube clip that captures the noise quite well. Any ideas guys? https://youtu.be/GL94S5oUHRw

Your help is greatly appreciated as always

Also, if you listen right and the end you can hear the noise as the engine shuts down Iit does this pretty much every time, and feels like something running as the engine rocks for the last time after cutoff.

Sounds to me like a broken engine or gearbox mount, probably the former.