410 rear driveshaft getting VERY HOT

[nobby]

Can anybody help?
I'v been running my 410 for about 6 months now, and i'v never had a problem with the car until the last month.
The rear inner driveshaft has started to get VERY HOT to the point of the thread lock on the grub screw that holds the Bevel gear to the driveshaft melted, and fell on to the cells, melted the case.
I'm using D joints, and the drivetrain feels free.
There is quite a bit of play in the drivetrain I.e. D joint barrels.

I have been running in doors.
Here's a quick breakdown of my setup if it helps:
Front diff 7000wt
Rear diff 5000wt
D joints
6.5 hpi flux pro
Gearing 87 24


The motor does get warm, but nothing out of the ordinary.
It's just the normal Durango heat, but the rear driveshaft is really starting to concern me as it's red hot.

I'm racing outdoors at the oople series at stotfold this weekend so I would really like to figure this one out before I get there.

Any help would be much appreciated.
Cheers.