H78 is for my reference.

Vintage Stanley knuckle joint lever cap parts lot, 1-5/8" wide and tops has a B-Casting mark. The lever cap that is mostly complete is just missing one pin, and there is one back section of a lever cap and, and two front sections, one of the front sections has cracked back section connected but does have the pins. See pics for best description, you can make 2 good lever caps but you will need a pin or two. 

Fits Stanley no 18 and 19 knuckle joint block planes.

Comes as seen in pics, any questions just ask.