Jeffries and Fitz deserve mentions... at least for their era. Joe Louis An honorable mention should go to Tommy Morrison. When he applied pressure to the body, he got his opponent's attention.
Jeffries was moster body puncher, he didn't even try to find head. Fitz is of course among the best ever. Joe Louis is in conversation like in any punching category.
George Chuvalo was a dedicated body mauler. Frazier might have been the best. Unless you stopped him early, you were in for a long painful night gasping for air.
Joe Frazier. He was committed to punishing the body. Solid shots with both hands. His right to the body was wicked too. Honorable mention Evander Holyfoeld.