Quote:
Originally Posted by bill3rail
What is the difference between 3 digit option and 6 digit option SPID's?
Were they changed to 6 digits after specific year?
Bill
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The actual RPO code is always the three characters in the middle.
The additional characters (when used) provided more info about the RPO code, like clutch type, etc. When those fell into disuse they were often replaced with just dummy characters to fill the spaces, which is obvious when all of the RPO codes have the same leading and ending characters.
There was no specific breakpoint for changing over to the pure three digit code, and it varied by plant and model year even through the squarebody era.
K