They're physically diferent. You will end with a broken flatcable though. A 400C laser will fit wonderfully in a V4 but won't work properly on anything earlier than it. Electronically, it works but the physical shape of the 400C laser will make the ribbon cable to bend and break at the outter edge of the mechanism.
SCPH-10000_GH-001 SCPH-15000_GH-003 SCPH-18000_GH-008 SCPH-30001_GH-005 SCPH-30000_GH-016(V4) SCPH-30001_GH-010(V4)
2xSCPH-10190, 2xSCPH-10350, 2xSCPH-10280
"**** j0 hackers!"
-Sjeep (As seen on TOXIC OS ELF...)