Wow, Chris that turned out great. The P/S bracket on my cars was also unpainted, so that is a mirror image of what was on my Mustangs and Torinos.
Except for a few Saginaw applications, this was the corporate PS pump for automotive and light truck applications from 65/ until the Ford C II pump was used starting in 1978. With the sheer volume of pumps and components used during this time frame, it's not surprising to find two different color metal reservoirs for production and service parts. The teal pumps on my '71 Mustangs and '72 Torinos were original to those cars.
You would have to talk to the guy in Tucson AZ who owned it... Do they even have grass there to cut? this was "matching" AC idler pulley... I was not aware that parts were interchangeablegable between John Deere and our car's. learn something new every day!
All of mine are black have 8 of them 72 & 73. I thought the blue ended in 70?? The brackets for PS and AC use the Manganese Phosphate coating like the hood hinges, upper shock mount, hood latch, parking brake and gas pedal bracket do. I do mine at home but some plating shops have the solution. Gun shops use it and they call it Parkerizing. Ford used manganese phosphate and GM used zinc phosphate. You will need a big stainless steel container to heat the solution in mixed with distilled water. 190 - 200 deg. F. I seem to recall. Next time I do some will take pics of the steps and process. You do need to clean all grease and oil off with oven cleaner and then glass bead the parts before you coat them. They spray several times with WD-40. Was thinking about trying coating in wax after also. Here is where I get my chemicals. https://www.palmettoenterprisesparkerizing.com/product-page/one-gallon-of-each-zinc-manganese