I had thought it was Devil His Due and it was. He was a really nice looking, almost jet black horse. He was a serious runner. First time I saw him at the track I just knew this was a race horse
This story by Barbara Livingstone shed some light on it. I swear I saw IRS in the owners listings in the pp's on his races at one point.
He was a real good horse.
https://classic.drf.com/blogs/giving-devil-his-due
There was a mention that he never raced on Lasix. Most of his races were in NY and it was still outlawed back then there. Allen wouldn't give a horse Lasix if he didn't need it.