Copo 396 9627 motor found suffix I5 ? help!!

[964IMPALA]

Hi,i posted on the Impala net forum that I found a weird 1968 396 with a I5 suffix
And they say I may have a real COPO motor
Here's a picture and what I found so far,
Any help much appreciated.
5th line down shows a I5 suffix
On a COPO 396
396ci/325HP L35 IG IV IA
396ci Police IN IF IK
396ci COPO 9565 (313HP) IY? IW --
396ci COPO 9559 (IZ, I2, I3, I4)
396ci COPO 9627 (I5, JB)
427ci/385HP L36 -- IJ IH
427ci L36 SS427? -- IS IE
427ci L36 COPO 9626 (I6, I8)
427ci/425HP L72 -- -- ID

* Engine code for L73 and L30 with TH350, used in
late-year 1968 TH350 test fleet

[69LM1]

These are the "I" codes I see for 1968. None for I5, however there is an IV for a 396/325hp engine. Could it be possibly that someone used a 5 in place of a broken or missing V? I've seen substitutions in the past. Just a thought.

IF 1968 396 325 Chevrolet Police
IG 1968 396 325 Chevrolet
IK 1968 396 325 Chevrolet Police
IN 1968 396 325 Chevrolet Police
IV 1968 396 325 Chevrolet

/Rich