Question: are shimano freehub bodies interchangeable?
Answer: Most Shimano Freehub bodies are interchangeable. ... Shimano information on the 7800; 7801. FH-7850 and FH-7900 Dura-Ace bodies, which have returned to a splined attachment between Freehub body and hub shell, but it is larger than the usual one. It is similar but not interchangeable between these two models.