Not sure about a retention time frame. I scrap based on the reports in dealer connect.
Dealer connect > Parts Tab > Return section > Return Material Utility > Part disposition tab > Here you can print a scrap report or search by (Claim #, VIN, Part Number, and submit date)
I believe the warranty admin has 60 days from the job completion date to submit a claim.
On a side note watch any cores going back that are from a warranty job. Make sure it is in core status before sending them back. The warranty return gets priority over core status. If you send a core back and the warranty wants it you are screwed if you can't get the depot to find the core and send it back to you. (Don't ask how I know

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Send me a note if you want my contact info. steve.brittain at actonchrysler dot com