Going through this now with the windshield wiper assembly mount.
The factory unit measures 32mm (1.25") long and is roughly 13mm (1/2") wide. The flanges around the base are roughly 3/4" and these are M6 studs. Envision a quazi-hourglass shape or I-beam would be a better description.
The closest unit that McMaster has seems to be 9376K208. It could very well be that these stretch with age. I only have the pieces of the old factory unit to go off and they seem to be longer than the longest one McMaster offers by 1/4"
I have a factory unit coming from a member here. For a couple bucks, I think I'll order the McMaster piece just to compare them and help others with the best decision.