Surefire's older style beamcovers/shapers were much more slender and lacked the locking cam lever, though they still have a prominent hinge and a tab for opening. Someone correct me if I'm wrong, but you basically take the 'M' out of the part # to find the older style. For example, instead of FM35 for the red filter, it'd just be F35. I'm not sure if they had an older style diffuser though, it would be a p/n F34 if so. If I'm incorrect, please correct me. :duh2:
I'm afraid it's not that's straight forward.
The Classic version of the FM35 was the F26.
Here's a quick guide to SureFire's BeamFilters...
FMx3 IR BeamFilters - Glass (I'm not sure of it's details)
FMx4 Beam Diffusers - POC's 'LSD holographic 20deg diffusion polycarbonate
FMx5 Red BeamFilters - Multi-AR coated tempered glass
FMx6 Blue BeamFilters - Multi-AR coated tempered glass
FMx7 BeamCovers - Hard Anodised aluminium alloy
FM1x (1.62" diameter) - "M3" Millennium Bezel, 9N, 9AN & KL6.
FM2x (2.5" diameter) - Millennium TurboHead bezel & 'KT' TurboHeads.
FM3x (1.25" diameter) - Standard "6P" bezel (tight on the G2/G3/G2Z).
FM4x (1.36" diameter) - Z32 aka Classic WeaponLight Shock Isolated Bezel.
FM5x (1" diameter) - ScoutLight, E-Series bezels etc
FM6x (1.47" diameter) - M2, 8X, 8AX/8NX/L7, KL3/KL5/U2 etc
FM7x for HellFighter (FM73 IR), (FM77 Amber*) & (FM78 Opaque*)
(* It would make sense if these were the other way around, but it appear not)
Classic BeamFilters for Taclight (Z32) (1.36" diameter)
F11 - Red
F12 - IR
F13 - Cover
F19 - Blue
F63 - BeamShaper (Medium)
F64 - BeamShaper (Wide)
Classic BeamFilters for 8-Series (& "M2") (1.47" diameter)
F62 - Cover
F66 - Red
F67 - Blue
F68 - Traffic Wand
F69 - IR
F70 - BeamShaper
Classic BeamFilters for 9-Series (& "M3") (1.62" diameter)
F32 - Cover
F33 - BeamShaper (Medium)
F34 - BeamShaper (Wide)
F36 - Red
F37 - Blue
F38 - Traffic Wand
F39 - IR
Classic BeamFilters for standard bezel ("6P") (1.25" diameter)
F16 - IR
F17 - Cover
F23 - BeamShaper (Medium)
F24 - BeamShaper (Wide)
F26 - Red
F27 - Blue
F28 - Traffic Wand
Classic BeamFilters for T-Series Extended Range TurboHeads (3" diameter)
F40 - BeamShaper
F46 - Red
F47 - Blue
F49 - IR
I'm sorry for it not being very comprehensive. Its difficult to remember everything....
Al