Radiator Hose Decoding question

[ORIGLS6]

Does anyone here have any idea how the codes on radiator hoses decipher? There doesn't seem to be any standard format that I can see.

Example: two 1970 Chevelles, both from the Arlington Plant, and built less than two weeks apart. The upper hoses have the same part number; 3942453 SV which is for a four core radiator, but the smaller codes vary drastically. One reads "EB 76 EX 5 0 02 20 7 0 K3" and the other is "76 EP 50 EB". All the print on these hoses are very clear so I know I'm not missing any numbers. And the lower hoses on these same cars read 3959188 SZ P/N and "C129 70K3" and 11139K3" respectively.

BTW, I noticed Red Alert still has the original upper hose so I'd be interested to see if the smaller code is still legible, and how it fits into this mystery.

Thanks in advance for any replies.

P.S. I'd also be interested in any pix you might have of original hoses, particularly '69 & '70 Chevelle and Nova.