8 lug on 6.5" 19.5 dual type wheels can be found with two distinct center or dish profiles. I don't believe this is relative to front or rear location nor wheel width or offset, just different style from different manufacturing time or place, I've had both and believe they had same part number.
The "cone" shaped center does not fit on the rear drums of our old trucks, or not likely to fit.
The "concave/convex" shaped center likely will fit.
Even with the concave/convex type 8 lug 19.5 wheel the center dish can be very close or too close to the drum. When I had these wheels on my 51 GMC 1 ton I cut the centers out of some old cast drums (from a 14 bolt) to make wheel spacers enough to clear the wheels on the drums.
