If you have a good welding shop or battery shop anywhere near you, you could have them make them for you out of double 00 welding cable. I know I paid over a hundred dollars at a dealer for the positive one, but that was 16 years ago, I don't know if they still have them. Rock auto has the negative only..Mark

Turns out that there are many online outfits that make custom cables, I had no idea:

https://www.google.com/search?q=custom+made+automotive+battery+cables&pws =0&gl=us&gws_rd=cr

Also, I don't know if they are similar, but eBay has them for the Cummins 2500, just put the following into an eBay search:

Mopar-Genuine-OEM-Battery-Cables-Connectors-for-Dodge-Ram-2500/179847/bn_30100900

...Mark

That happens to be the first one on the google list above, good job...Mark

i'd say make your own if you have the tools. that's what I did to get away from that initial cost.
I also soldered and compression crimped the connection, covered the end of the connection with marine heat shrink.
switched to the military style post terminals.
I had some parker cable and it was pretty heavy duty im sure a battery center near you can help.

I had the local NAPA put eyes on my old cable and had them order the POS and NEG HD military ends for the Barrery (ebay ads are not allowed on dtr, just post up the item #) Hope this helps Ken