Difference between DL380 rails for different generations?
HP DL380 Rail Kits:
G1 327310-001
G2 228894-B21
G3 300605-001
G4 359254-001
G5 359254-001
G6 574765-001
G7 616992 001
G8 663480-B21 (LFF) or 663478-B21 (SFF)
Note: only G4 and G5 are the same.
I would just pick up a third-party rail kit at this point. Otherwise, get the G5 specific rails from eBay. They are not interchangeable between recent generations.
See: http://www.racksolutions.com/hp