Just in case you have not seen it, this site has many of the mods from the lattest back to the earliest.
ftp://maikhaas.dyndns.org/Volume_1/S.../DR.%20DIESEL/
Only problem is that you have to search each folder to see what is availble. I called it a problem but I enjoy rumaging around in there so its really not a problem for me.
I'm still looking for the original Kiel Canal mod and one of the early Hydrophone improved graphics mods but no luck. If anyone has one of these I would appreciate your uploading it to the site. The site is run by Plisskin_04 and he would probably also appreciate any mod you may have stored away....at least he asked Sailor Steve for additional mods.