Hi Steve,
  
 I use a kit I bought in 1986 from Birchwood Casey for room temp oxide treating.
In it contains the rust remover, pre-dip cleaner and the black oxide solution and a can of Dri-Touch oil.
I still have solutions from that kit today and use it for spot treating bolts. Today there are so many more kits available.
 The trick to longevity is once the parts are treated and oiled initially you have to apply an oil to it periodically to maintain the rust preventative.
I use the Dri-Touch oil which goes on wet and dries to a film that provides the rust prevention. I apply it about 3 times a year with a small model type paint brush (I also apply to other parts too such as carb pieces and brake/fuel lines).
By itself black oxide offers no rust prevention but does provide a base for oil to bind to. The kits are the way to go for convenience and cost savings.

Mike

 Thanks all for the informative feedback.
And RP, I did appreciate the posting you have done for the research on the spring colors. The chart in the AIM is confusing for sure.
When I restore that car I'll keep what was there despite the differences in the spring application codes (YJ sticker in front and standard application paint in rear).

Mike

 That's is interesting there is a mixture of springs, RP.
My guess on that is one of two things happened:
1- The customer didn't order F41 and standard YG coil springs weren't available so the YJ was used to keep the line moving (shortage in customers favor)
2- The customer ordered F41 but the rear BY springs weren't available and BH were used to keep the line moving (shortage in Chevy's favor)
  Or, there is a third possibility in that the spring chart revised date of 3-3-67 shows a change in usage but the assembly line didn't incorporate it just yet in their process?
Maybe a fourth....I am going to study the stripe closer and see if it is coral and just the yellow hue is caused by the rust. What usage is the coral for?

Thanks for the feedback.

Mike

 Attached are the left and right side GM metal (aluminum ?) badges on my LOS 4B survivor (including paint).
On the left side you can still see the dealer service stickers glue.
If you can approximate the location by looking at the pictures that should get you close being they were put on by hand.
If you need measurements then I can get them for you.

Mike

  A (reputable) machine shop won't turn them if they are past the minimum for risk of liability.

Mike

 I seriously doubt it was balanced as a complete unit. It makes more sense in mass production to balance the components separately and assemble later using the individual cores so there is no need to have a match pair. If it were that critical then I would think there would be an index mark in case you have to unbolt the sections for things like changing a broken stud and putting it back together in the correct position. Even then, a replacement stud may not be the same weight so there goes the balance if it were ever replaced and the unit was balanced as a whole.

Mike

Not to add confusion but wasn't there 2 font sizes used in 69? I have a Julian date of 334 on the 9204 booster (no Delco stamp either) and the font size is approximately 1/8" in height. This booster must have come on an early build 69 model. The numbers in the images in this thread look smaller.

Mike

 Did 67 mono springs use P/N decals or was the 'color code stripe' mentioned in 67 AIM UPC 4 B1 used as an identifier instead?
My 67 LOS survivor has the F41 suspension as evident by the front coil spring tag P/N 3912532 YJ I removed (looking for a place to duplicate it).
On the same car is the paint code stripe that shows a definite yellow color as shown in the attached image in addition to the smoke gray spring color.
If I cross referenced my numbers right, the mono spring should be 3925817 BY (12437, L35 & F41).
To date I have found no info for the 'color code stripe' summary so maybe this one if a first for CRG?
My thinking is a paint strip was used in 67 and then a decal in 68 and up.

Thank you,
Mike

<<

Did all 9204 brake boosters have delco stamp in 69?                                                                                                                                                                                                                                                                                                                                            Thanks Latecode

>>

 Are you sure about that John? I have a 9204 from a 69 with a Julian date of 334 (had iit since 1986) and it doesn't have the Delco stamp.

Mike

Yes, they did, and the Julian date was stamped on the other side of the tab.

 What conditions are you starting with?

Mike

 Most will say to stay away from clear and for good reasons as It will yellow and flake off with age (been there and done that with clear lacquer & enamels).
I sprayed a new gas tank in 1987 with DuPont Imron polyurethane clear and when dried took the gloss down with a few passed of Scotch Bright for a natural look. To date there is absolutely no yellow or flaking.
 As for brake lines, they are protected by a variety of methods out of the box. But to keep oxidation in check I often applied a thin coat of Birchwood Casey Dri-Touch with a small paint brush twice a year to the lines and armor and they still are clean after 25 years.

 There are many opinions and methods, but this has worked for me in the long haul of 25 years.

Mike

 Thanks George.

 Looks like the Caswell kit is 30% off as a June sale for the 1.5 gallon.
http://www.caswellplating.com/electroplating-anodizing/zinc-plating-kits.html

Mike

 Thank you all!!  I can't believe to the most granular levels of details we let ourselves ponder 
Time to black oxide the bolts now....

Have a happy and safe 4th if I don't get to talk sooner.

Mike

Hi Marty,
  I've read that informative writeup a few times but don't see anyplace mentioning rear bolts installed. I would think it was risky to ship a heavy rear with the studs hanging out and getting dinged and yet I don't see when it was installed.
I guess a judge could chime in and give their take on how that would be graded...painted or not.

Thanks,
Mike

Hi Jeff,

  You're right about the semi-gloss. I left the semi out which is what I meant.
As for the springs coming later, being that was done at the Chevy plant and the rear assembled and painted elsewhere, I'm not sure if the bolts were installed before being shipped. I am assuming they were because I don't see the bolts mentioned in the AIM though the drawing shows the studs. It seems to make sense if the bolts were installed and the studs masked before painting so as not to cause skewed torque readings later from paint on the threads or they were installed after the housing was painted so the bolt finish would be black oxide ( or phosphate).

Mike