Correct Style Radiator Cap

[69BFan]

Does anyone happen to have or know what radiator cap was used back on these cars when they came down the assembly line?  From my understanding, the "small" rivet style was used up and into the 1970 model run.  At some point, Chrysler transitioned to the "larger" rivet style cap. 

The second question is that the "larger" rivet caps were found without and with the "SMCO? stamped around the perimeter of the rivet.  What is the correct style of the "larger" rivet caps for the 70 to 74 model years?  Were both used?

I have attached a picture of an original "small" rivet cap.

Thanks for any and all input.

[usraptor]

 

[headejm]

This is the "original" radiator cap for my 1970 Challenger, 383, AC, automatic, 26" radiator. I say "original" because I've only owned it for 40 of it's 50 year. I believe it's original.

[MoparCarGuy]

This is the "original" radiator cap for my 1970 Challenger, 383, AC, automatic, 26" radiator. I say "original" because I've only owned it for 40 of it's 50 year. I believe it's original.

The date-coded center rivet shows K9 which is October 1969. ORIGINAL!

Reproduction caps differ for the center rivet but can be had for between $14 and $22, depending on the vendor.

[69BFan]

This is a picture of the current reproduction of the small rivet style cap.  It is a 16 pound cap where the picture posted of the cap for the 70 model 383 car with AC shows it to be a 15 pound cap.  A guy with a 12/16/69 GTX Survivor sent me a picture of his original cap and it is very close to the reproduction that I posted. 

Still interested in any information as well for the large rivet style cap that are 16 pounds.

Thanks for the input guys!!!

[7E-Bodies]

I wouldn't mind finding more info on repro caps as well. The one that was on my numbers matching 70 440 is incorrect I'm told. I was also told that an OEM or NOS can go for upwards of $400! No thanks. Not a hemi car. A close and reliable repro will do fine. I'll add a pic of mine in a bit.

[EV2RTSE]

These are supposedly by the same company that made them back in the day-

https://www.amkproducts.com/parts/chrysler/