I use a Comma ATF over here in my R380, as you suggest there are many different opinions on this one.
This is what Gomog has to say on the matter.

Don't get talked into converting to a Borg Warner T-5 Transmission. That is what I used when I built My +8 Bitsa. My T-5 works well but I had a mis match of parts to start with. I have driven +8's with the Rover transmission and it worked very well. Maybe better than the T-5 at least as good. I think some +8 Racers in the UK like the T-5 for some reason I am not sure why.

Oh no I am not switching transmissions, I have a T5 in my TVR Griffith 500 and while the T5 has a taller and more useable first gear I think they are both excellent transmissions . For the most part I start the Morgan in second gear anyway it’s a 4.6 dynoed at near 300hp and buckets of torque .
I have just removed seats tunnel and transmission cover to remove the shift assembly and found some play in the 2 nylon ball joints , not a great deal but I will take care of it tomorrow then I think I will change the oil again while it’s so easy .
Then I suppose I will have to wait until Christmas is out of the way before I can give it a good test run .
Cheers Dave

John...replacement “cups” for the gearshift are rarer than hen’s teeth. Even rarer than a politician who answers questions!
UKC 3159 is the part number. They have a weakness where the tab snaps due to fatigue. Mine had been welded by a previous owner but strengthening tabs need to be added. I made a small bracket to beef up mine and bolted it above the fixing tab. I also dribble a bit of oil down to reduce friction against the gear lever ball that sits under it. The gear hange is much better with the repaired cup.
A thought........ it appears anyone with the R380 or LT77 box seems to have the issue long term so I wonder if some could be made by an enterprising engineer with access to a suitable press. I guess set up cost and volume are limiting factors though.

There is also the UKC8764 dust cap which is basically the same as the UKC3159 but the UKC8764 needs some slots cut in it to match those in the UKC3159. I think the UKC8764 was used on the LT77 remote. I used one on my R380 box last year. It is listed by http://mgrovergenuine.co.uk/ but currently out of stock, may be worth asking them if they will get stock.

Yep, I built a tab from some scrap metal and pop rivetted it on. 6 months later Rimmers finally sent me a new one.

Many thanks for the input guys but it looks like it’s gearbox out sometime in the future.
I removed the remote shifter housing and shimmed out a small amount of play in the bushings I also found one of the bell housing bolts had come loose and was touching the bulkhead which I thought was promising , after refitting the bolt and changing the oil for Mobil 1 75/90 synthetic I put the whole thing back together and out for a test run today . The noise is still there though I think possibly reduced , perhaps wishful thinking or the fact that it was cool out today .
It’s prevalent as I come to a stop or slow to a walking pace , doesn’t matter if it’s in gear or neutral , clutch engaged or not it will persist until about 5 seconds after I reach a complete stop then disappear , it sounds quite fast like engine speed rather than road speed and isn’t affected by increasing the engine speed .
There is a small bearing between the gearbox input shaft and the main shaft that is currently the prime suspect but it will have to wait untill I am home in Canada 2000kms away , perhaps a next winter project .
Cheers Dave

Sorry to hear that Dave. Good luck.