Harley Davidson Seat T-Bar Mount XE-39

According to Palmer's 'How to restore your Harley-Davidson', 51912-35 was originally forged with the ID XE-39, but it was changed in the 1950s to 51912-35, and this stayed until the late 1960s, until another version was introduced which had a broader front mounting bolt slot.

51912-35 should have 2 seat pin positions - the forward hole is for Big Twins, the rearward for 45s.