I just cleaned up my coil bracket by soaking it in Evaporust. Looks to me like the bracket was originally dichromate finish. I can still see remnants of rainbow coloration. Am I correct?

It doesn't sound correct, post some pictures.

Not the best pics but I the flash washed out some of the color.

and here:

As far as the coil bracket goes I have seen enough variable to say that is likely original. Silver to gold colored plating finishes varied A LOT on most small plated components, likely due to vendor or manufacturing batch to batch variables.

Ok, you made me go digging. I hoarded these coils up over the years. These are both from 71 Small blocks, the one dated 330 is from an early 71 340, the other might be from a 318, I'm not sure. They are identical in every aspect except the date codes (which are also pretty close). One of the brackets had a gold finish and one has a bracket with a silver finish, these have never been apart and enough original plating is visible to confirm both as genuine.

Both of these have "Made in Canada" embossed in the tops. They are also quite a bit shorter than the other 69/70 coils I have.

Showing the two shorter coils next to two of the longer ones.

Notice how the date codes run across the coils on the short versions and lengthwise on the taller coils. Also notice the gap in the part# ink stamping on the taller coils which is not present on the short coils.

Last one

I would like to refresh this post for all the information that it is generating.
I would also like to add my engine to the others.
A little history of the car,
1971 Plymouth Cuda,Sassy grass Green 4 speed SPD feb 71
* means not original to engine
Engine color Orange
Block cast 8-30-70
Block assy info stamping CW340P34260406 assembled Dec 14,1970
Intake manifold cast date * 10-22-70
Waterneck 2780970
Oil pan stamped 294 no welded tabs
Temp sending unit stamped 250 date M1
Waterpump housing 2951698 Date 10-70
* Carb 4972S Date I 0
Heads J

That's all I have for now.
Can't figure out the date code on carb.
Thanks and hope this helps with the research,it is sure helping me.
Bob T.

Two items confuse me on that;

First the M1 temp sending unit sounds like December 1971, a year late?

The carb date code did not use an "I" because the skipped the letter "I" in the date coding. Post a pic of that one if you can. My guess is that it's an H or a J

The temp unit must have been replaced at one time.After a better inspection of the date code of carb it is J 0.The carb is not original to this engine.The engine had aluminum valve covers on it and I will be going back with OEM covers.A question,what did the OEM cover bolts look like?Pictures would be great.Thanks for your input.

There were various hardware vendors for engine bolts, I'm sure it varied year to year and assembly plant to assembly plant. Here is an example of an early 71 340. It is the only style I've seen from the Windsor plant on 71 340's.

Thanke You Scott for the picture,that helps a lot.I looked in my nut and bolt stash but couldn't find any.Anyone know where I can find a set?Also need oil pan bolts.
One more question,what is the carb date of J 0,and is it in the time frame for this assembled engine of Dec 14 70?
Thanks in advance

Sorry, can't help you on the bolts. From what I've observed the correct bolts are not sold anywhere, you'll need to scrounge them off of similar vintage engines (not easy). Be forewarned, there various vendors on ebay and other places that sell "O.E." correct bolts and they have completely different markings. They may be right for some small blocks, some years, but when it comes to the original 70-71 340's I've seen, they are all wrong.

J = September 0 = 1970 = Perfectly acceptable on your December 14, 1970 assembled engine.

Oil pan bolt from a survivor 1971 340 assembled in September of 1970. Before removal:

Since you can't see through road grime and corrosion I pulled one and bead blasted it, all have the same markings. Study closely, it's similar but NOT the same exact head markings as the valve cover bolts.

After I replaced it

Thank You again.I will continue my search for the right bolts.This is a fun project,and this post has helped me a lot.