The third set in the file #8 is the best one among those.
How about to practice to pronounce actual words that contain "r" sounds? "R"s at the beginning of a word and the ones in the middle or at the end of a word are slightly different. The pronunciation we are talking about here is for the former ones.
In my Pimsleur Japanese, there are a few times I've heard it sound like an "l", and then another speaker will say it with an "r". I guess they are doing that so you start hearing the possibilities...
I'm going to try and upload another one as I'm trying to change the way I say the letters a bit but I believe that It will be still wrong. But that's ok.