I just picked up a new GN Grain door PS-1 from Stockyard Express today (FYI, They are stocked to the roof right now if you haven't been in a while. Wow!). This is my first car with the new truck design. It is extremely easy to convert to Kadee couplers. The included spacer and screws make the job simple. I especially like the little posts on the spacer that holds it snuggly while mounting the box. Here are some photos of the process:
It may be a bit of a high rider, but for 3RS it doesn't bother me. It's such a simple process that I won't bother going any further.
If you are wondering, it only takes removing 2 more screws per truck to convert to 2R.
Really a great design by Lionel. Well done.