Tim, after cleaning of the road grime off the bolts for the extension housing (tail piece), the servo cover and cross brace insulator all the bolt finishes look the same and they are phoshated not black oxide. There is a spring clip (don't reallyknow what it does) and some tiny wave washer and spring clip which are black oxide. To verify the bolts I bought ambolt finished in black oxide and cleaned it the same way as originals and the finish was unaffected. So I have to say my servo and tail bolts were phosphate originally. The manual linkage rod may just be weathered phosphate which turned light gray from age. The brighter silver may be scratches down to bare steel from fasteners.
Searched for the converter color code on case with a magnifying glass with no luck. Gave up searching for it on the web. Went to refinish the converter instead. Lucked out because the converter color code survived all these years. Small Paint slash of mustard yellow/dark grabber orange. The only paint mark found on the original silver jade converter paint.
