On the top of my head I can only think of 4
Paul McMullen (175 lbs - 3:54.94)
Josh Kerr (165-175 lbs - 3:48.87)
Chris Solinsky (172 lbs - 3:57.89) *Before his weight loss in 2010, he admitted to weighing an additional 10 lbs*
Nick Symmonds (165 lbs - 3:56.72)
I always wondered if Nick Bare could do it with the 190-195 lbs he ran his Sub-5 in. I know it's a dumb question but, I remember in the Batman comics. He and Robin are capable of running Sub-4 despite Batman weighing 210 lbs and being able to bench 1000 lbs.
Anyhow, any legends y'all can source? Heavier Distance guys are always a W.