Its probably the left mount that is shot. Because of the direction of rotation, under deceleration or in reverse the mount is compressed. When the rubber is gone its metal on metal & it sounds horrible. Under acceleration the motor lifts on the left mount.
The left mount is more likely to fail because of the fuel system being on that side. Mounts dont like a wash in diesel, the rubber soon degrades & fails.
I would do the left mount first & see if there is an improvement.

Good Luck

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving