Block (letter located in front of #code next to filler tube)
ZN=230/250 1bbl auto
ZD= 230/250 4bbl stick
ZK= 230/250 1bbl stick
ZE= 230/250 4bbl auto
ZH= '69 250/230HP 4bbl 4spd
ZC= '69 1bbl stick
ZF= '69 1v auto
ZL= '69 4v auto
I dont know how to decipher the block #s after the code. As you can see, some of the letter codes can be a 230ci or 250.
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Heads

Year Cid HP Cast
1966 230 165 9782005
1966 230 207 9782229
1967 230 165 9778692
1967 230 215 9778693
1968 250 175 9791194
1968 250 215 9791195
1969 250 175 9795456
1969 250 215 9795457
1969 250 230 9795457

Cams (letter located behind sprocket)
A =165HP 1966
B =207HP 1966
C =175hp 1967?-69
D =165?hp ?
E =215hp1967-69
H =230hp 1969 only

4bbl Carbs
702_26_
Blank indicates year and trans/ Example 7028260=1968. 1=stick, 0=auto.

There are some 703____#s for A.I.R. systems, found in parts manual.

The ? marks are from known memory lapses or unsure things. Some others may be able to correct some of my mistakes or unknown memory lapse
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Edited for some mistakes found so far