US NA/NB Miata Rear Suspension Crossmembers: Generation, Braces, Geometry and Contents

No formal NA chain is asserted among NA23-28-800, N007-28-800C, N007-28-800D and NA75-28-800C because the checked early EPC exposes build/VIN annotations but not a complete US supersession history; identify the installed frame and recipient VIN. NC10-28-800A versus NC10-28-800D are treated as 1999-2000 versus 2001-2005 NB catalog branches, not an automatic A-to-D replacement arrow. NC10-28-E90D and N067-28-E90A are separate rear cross bars, not subframe supersessions. No NA-to-NB chain is published from shared arms, stop washers or seller compatibility language.

Begin with both VINs and classify NA versus NB before comparing the exact stamped/service identity. The checked sources support separate NA and NB catalog families; shared upper/lower arms, cam hardware or mounting points do not prove whole-frame interchange. Mike's groups 1990-1993 without tabs and 1994-1997 with tabs, but the other checked public catalog and seller paths do not establish a complete year-by-year NA tab history. Treat that split as a seller claim, not an OEM interchange rule, and do not buy by year alone. Require clear photographs and measurements of the actual brace tabs, body studs/holes, differential and Power Plant Frame interface, upper/lower-arm and eccentric slots, sway-bar brackets, exhaust clearance, brake/parking-brake routing and every mount. A bare, loaded or complete frame does not prove arms, cams, differential mounts, cross bars/braces, sway bar, lines, shields or hardware. Reject or obtain qualified structural review for perforation, deep scaling, bent pickups, cracks, torn/elongated slots, collision movement, filler, heat, non-factory welds or coating that hides repair. Inspect the vehicle-side rails/floor and compare fixed points because a replacement frame cannot correct body distortion. Use rated support and current Mazda procedures, preserve eccentric positions only as a starting reference, replace specified hardware, and perform a qualified alignment, brake/parking-brake and road-safety inspection.

A VIN- and generation-confirmed new OEM service frame or a straight, measured genuine used donor is the checked stock-service path. New aftermarket NB frames are advertised in some non-US markets, but an OE reference in a listing does not prove Mazda manufacture, US fitment, material, coating, geometry or road-use acceptance. Poly/solid bushings, brace conversions, reinforcement plates and fabricated drift/swap cradles are not Mazda supersessions and can change isolation, geometry, exhaust/brake-line routing and load transfer. Powder coat or fresh paint does not prove straightness and may conceal corrosion, heat or repair.

US/LHD NA 1990-1997 and NB 1999-2005 only. Match both VINs, generation, exact frame identity, actual brace-tab/cross-bar pattern, differential/PPF and arm/cam interfaces, geometry and every included piece. One checked seller publishes a 1990-1993 versus 1994-1997 NA tab split, but the checked evidence does not establish a complete year-only rule; verify the actual pattern and never infer NA/NB interchange. Reject perforated, bent, cracked, torn, cut, welded or concealed repairs; inspect vehicle-side structure, freight and returns, then use qualified support and alignment procedures.

Supersede reviewed 15 unique research sources for this guide. 7 also appear above as a seller or official action and are not repeated here; 8 additional citations follow.

Research last verified 2026-07-29.

1. Mellens — 1990 1997 supplementOpen source
2. Trull — NB collision guidepdfOpen source
3. PartSouq — source pageOpen source
4. PartSouq — diagramOpen source
5. Foxed — MX5 93 2 OF 3 CHASSISOpen source
6. Mazdamotorsports — sus rearOpen source
7. Carmanualsonline — mazda mx 5 1990 workshop manualOpen source
8. Classicmazdaepc — source pageOpen source