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RAM
RAM does not have a specific procedure for replacing the front upper rail.
Per the 2015 Ram 1500 body repair manual: "Service assemblies for body components may be disassembled if utilization of the subcomponents is more appropriate to the repair or to reduce vehicle disruption."
Check out the I-CAR Collision Repair News article: FCA/Stellantis: Welded Sheet Metal Repairs and Replacements