Second on the 14CUX being interchangeable with no programming. However, the 96 and later GEMS one's have to be programmed for the truck ahead of time, or the security system will immediately lock the computer and there's nothing you can do in the field to get it started. I don't think the ECU's are unreliable unless they are subject to water/corrosion. Even in that case, you can open them up, dry them out and spray them with some circuit board cleaner and they will often work fine again. I have a good spare GEMS ECU from a 1996 Disco if anyone is interested in buying it. I bought it as a spare for my 96, but I am retiring the truck for parts or possible sale, so don't need it any more.
"The most unreliable car in the world is the most reliable car in the world." -Jeremy Clarkson
"Adventure starts when everything goes wrong." -Yvon Chouinard
1999 Discovery Series II "Oryx"
1989 Range Rover Classic SWB "Addax"
1992 Range Rover Classic SWB "Green Buffalo"
1995 Discovery V8i "Crikey II" (Sold)
1996 Discovery SD "Crikey I" (Sold)
2001 Jaguar XJ8L Vanden Plas "Prince Harry"