I assumed an existing loan for the balance of a 2008 3320 last December in order to take advantage of the 0% interest. It was the best way for me to get the tractor, and it worked out really well for the seller also who just needed out of this payment (tough economy).
I found the tractor on Craig's List and the seller already had quite a bit in equity in the package but still owed around 14k. As a rule when buying anything like this I make certain that I have all the information about the lien before making the offer, as the only other alternative to assuming the loan - in my opinion - is to send a payment directly to JD Credit in order to make certain the seller does indeed pay off the lien.
A couple of notes on the process:
1. The initial request for loan assumption has to come from the current owner - he will need all your information when he calls JD Credit such as Name and Address and Phone number.
2. JD Credit will give you a call and confirm that you indeed want to assume the loan, and then fax you a loan form to fill out and send back to them. As in your case, it probably helped that I had a JD Credit account in good standing with them already.
3. They will run the credit check on you, and then send it in to the JD Credit Loan Assumption dept (one person actually approves all of these I was told), and if everything checks out, they will fedex you the loan assumption packet for both the seller and you to fill out, have notarized, and return.
When I assumed the loan, it did take around 2 weeks for the process to work, and in the end I had to talk directly to the loan manager to request the process be expedited a little. This was just before the big snow storm over Christmas, and I wanted to take advantage of the snow thrower that was part of the deal. In the end, the JD loan people were VERY PLEASANT to work with and the process went smooth.
there was a point when one of the JD Credit agents said that they rarely approve these transfers between private parties (with no dealer involved), but apparently they let this one go through.
The seller was happy to get out of the payment, I was happy to get more tractor than I initially was planning to buy with no cash out, and I got the tractor just in time to deal with the 24" of snow we got over the next few days.
Good luck with your purchase
