Hi Andy,
Where are you based ?, I am in the same pridiciment, as I m wanting to put an auto in my 84 90, I have the 200 engine already out of my old Disco, I know some peole have got a 200tdi bolted to a range rover box but unsure if thats ok with the ratios as for 300tdi box I know a standard 300 engine can be bolted to an edc one so pretty sure a 300 box would be ok, so if your like me you are giong to be searching for a scrap 300 auto as 200tdi auto's are as rare as rocking horse poo ,
Hopefully some one might come along who has alreay done this & set us straight
John