Hi Jim - I've been doing 5/3/1 for several years and just wanted to share my "partial success" story. I've wanted a 500lb deadlift and 5/3/1 was able to get me to 480lb but that was over 2 years ago. After multiple resets, I still was not able to break my 480lb plateau. Being 53 years old, 6'3" and 185lbs, I know what you would have said if I asked you for advice (eat more!!) I like to play jumping sports, basketball and volleyball so I don't want to increase my weight much.
Anyways, I hired a trainer earlier this year and he finally helped me reach my goal of a 500lb pull. Here's a link to the video:
So thanks and ignore the dance at the end of the video!