If it were me ,I would go with the store bought rebuilds for the reason that is what they do for a living . Correct tools , methods etc. The local indy who only does it a few times a year lets say most likely won't do as a quality job as a remanufacturer. I have rebuilt many calipers , brake cylinders and master cylinders over the years. To be honest, what you pay for a rebuilt vs doing it your self is about even. Plus you just bolt them on , bleed and go.

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'83 240D 264k on 100% biodiesel/ 31mpg
83 300D 217K the $800 gem
'82 300D 267K the new WVO project car finished and driving for free
International tractor B275 on B100
Ford 555 backhoe on B100
Sargent 25 ton Rough Terrain crane on B50