WARNING: Harsh "CLUNK" when going from "R" to "D" can be the sign.
Check that rear axle & A-frame bushings are not the cause first.

The above warning is just that, a warning that could possibly save you from serious damage to you transmission and/or transfer assembly.

Is your Disco suffering from the dreaded "CLUNK"?

We're finding more and more Discovery's fitted with Automatic's that are coming in Clunking & Banging when shifting from "R" to "D"... upon inspection we've found that these cars too have NOT been up-dated as claimed by some dealers and even LRNA. My '94 (5-speed) while still under warranty was in a Dealer, while there I asked them to check that it had the up-dated INPUT gear in the transfer... I was told, "It's ok!". Some 2 years (give take) it failed! Why? It did NOT have the up-dated gear! The DLR never looked. 

This is a fairly simple fix on Automatic cars, but all the same it MUST be fixed. 
FTC5087 Input Gear & FTC5090 Tail Shafts MUST be replaced. 
It is suggested that the oil level in the transfer be increased to keep splines lubed correctly (increase by .5 of Quart).
This job is normally under $900.00 to complete.
We have found this problem even on 1996 cars with 75K miles.

The same failure is common with the Discovery & Defenders fitted with 5-speed gearbox; However it is not a quick/cheap fix as it normally requires replacing the 5-speed gearbox!