I had a problem with my 1994 Disco I, 3.9L v8. After the truck was warmed up, at idle the exhaust would make a rattling, kinda like soft backfiring sounds, which went away when I accellerated. Someone suggested the catalytic converters were failing. I had those checked by a muffler shop and they were OK. Still had the sounds...decided to look under the truck while it was running and making the sounds, and the main muffler I could see was pulsing with the sounds. Took it back to the muffler shop and sure enough, the muffler was shot...although the truck was very quiet other than those sounds at idle after the engine was warmed up. Replaced the muffler and now all is well. Fairly standard muffler. $72.00 installed.

 

Glad you got it fixed,,now just use high temp paint and
put Land Rover on it and put $200 in a jar and you can have some mad money!!!!!!!