The 500 and 600 series were the first "L" frame revolvers. The 19 and 66 were "K" frame revolvers, and were fitted by a pin driven transversely through the top of the frame. Later versions of the "K" frame guns left out the pins.
The cylinders of the "L" frame guns are larger in diameter. Therefore, the distance between the cylinder pin and the edge of the cylinder are different. For that reason, I think the extractor rod might not position correctly in the corresponding groove in the underlug. It might be close.
I don't think it's a simple screw out and screw back in proposition. On the other hand, a gunsmith or a good lathe operator could probably make it work with a minimal amount of bother.
Frankly, I think the underlug is an abomination. I'd rather have a light barrel on the "L" frame revolver. I've considered grinding the monstrousity off a couple times.