3/16" thick would be my guess, rs. IIRC, Scrap Yard hasn't produced a knife thicker than that with a mudder handle. And if we're talking through-hardened SR101 and INFI, that's PLENTY thick enough for a 5" blade.
I hope it is NOT thicker than 3/16" (0.1875"). I might be O.K. with up to .20" (????).