Can you ID this mystery part on my Y-BlocK?

[AllenV]

All,
On my 55 F-100 project https://www.fordbarn.com/forum/showthread.php?t=273280

I have spotted an unidentified bracket with a nylon roller on a post. It is attached at the left rear, see photos, marked with a red arrow. This motor is a 292 transplant mated to a T98 4-speed. Based solely on the oil pan and dip stick (photos) it seems it came from a non-truck.
The block casting is. EDB 6015E above the oil filter
The head casting is ECG-T

Can anyone tell me what this nylon roller part is? Is has no function on my truck.
Allen