1989-1994 S13 240SX Factory Automatic Transmission Assembly Identification

No complete-transmission supersession is asserted. Nissan's checked catalog shows 31020-45X06 through 07/1990 and 31020-45X64 from 07/1990, each with only an opaque MultiSupersession label; that is not evidence that either unit replaces the other. Supported component service chains are 31100-41X06 -> 31100-43X03, 31100-41X78 -> 31100-42X80, 31036-41F00 -> 31036-41F05 and 31036-53F00 -> 31036-53F01. The shared RE4R01A family name does not prove case, bellhousing, converter, valve-body calibration, connector, cooler-port, tailhousing, output, speedometer, mount, driveshaft or shifter interchange.

Start with the 17-character VIN, US/LHD identity, production month, original engine and proof that the car was factory automatic. The catalog places both complete-assembly branches at the July 1990 boundary, so a seller's model-year range alone cannot resolve an overlap car; use VIN/build data, the installed transmission model/number tag on the right side of the case and full-unit photos. Match the case and bellhousing, rear extension/tailhousing, pan, selector shaft, terminal cord and connectors, inhibitor/range switch, revolution/speed-sensor interfaces, cooler-port threads, dipstick/fill interface, mount pad, output splines/seal and converter branch. Diagnose TCM, harness, resistor, solenoids, sensors, inhibitor switch, selector adjustment, fluid condition and cooler restriction before condemning the gearbox. A used assembly does not prove inclusion of the torque converter, TCM, dropping resistor, vehicle harness, shifter/overdrive/shift-lock device, cooler tubes or radiator cooler, dipstick/fill tube, mount/crossmember, driveshaft/yoke, speedometer parts, flexplate/drive plate, fasteners or fluid; require an itemized written contents list. Require donor VIN/build/engine, readable tag, mileage documentation, road/yard test method, shift and lock-up evidence, fluid color/odor/debris, leak and case/thread condition, shaft/endplay evidence, converter hub/pilot/pad condition, return/warranty, core and freight terms. When installing, keep the converter correctly seated in the oil pump, inspect and clean the cooler circuit under current Nissan/remanufacturer instructions, and use the current exact-unit fluid and fill procedure rather than an old generic specification or dry capacity. Automatic-transmission removal, converter seating, cooler service and diagnosis require suitable lifting equipment, current service information and trained help.

Both exact Nissan complete-assembly paths were discontinued in the checked live catalog. A remanufacturer vehicle selector and used-salvage paths exist, but no generic RE4R01A, 1989-1994 or 89-93 listing is treated as interchangeable evidence. Require a written build tied to the exact 45X06 or 45X64 branch, VIN/build/engine, case/tag, converter identity, external-electronics responsibility, cooler and selector interfaces, included components, core, freight and warranty. One converter manufacturer's broad OEM cross-reference is retained as a search lead only; confirm the exact converter branch and application directly before purchase. Component diagnosis or a documented rebuild of the original unit may be preferable to an unknown donor, but this page does not publish internal hard-part, valve-body or performance-build interchange.

US/LHD factory-automatic S13 only. Match VIN, production month, original engine, right-side case tag/number, complete case and interface photos, converter branch and written contents. The catalog breaks at July 1990; model year or the shared RE4R01A name alone does not establish early/late, truck, S14, import or cross-engine interchange. TCM, harness, resistor, sensors, shifter/shift-lock, cooler plumbing, dipstick tube, mount, driveshaft, flexplate and converter may be separate. Diagnose controls and cooler condition before condemning a gearbox. Seller availability and contents change; no public new or used price range is recommended. Use current exact-unit service/fluid instructions, correct lifting equipment and trained help.

Supersede reviewed 21 unique research sources for this guide. 4 also appear above as a seller or official action and are not repeated here; 17 additional citations follow.

Research last verified 2026-07-28.

1. Tech 240sxone — 1989 nissan 240sx service manualOpen source
2. Nicoclub — service manualOpen source
3. Nicoclub — service manualOpen source
4. Nicoclub — service manualOpen source
5. Crbscca — Nissan 240SX 1992 35Open source
6. Charm — Automatic Transmission IDOpen source
7. Charm — Component LocationsOpen source
8. Charm — Initial Inspection and Diagnostic OverviewOpen source
9. Charm — A/T Excessive Engagement Shock/Shift LockOpen source
10. Charm — OverviewOpen source
11. Nissan Parts Deal — auto transmission transaxle fittingOpen source
12. Nissan Parts Deal — torque converter housing caseOpen source
13. Nissan Parts Deal — auto transmission control deviceOpen source
14. Gopnh — Search ResultsOpen source
15. Nissan Parts Deal — nissan transmission assy automatic 31020 45x06Open source
16. Nissan Parts Deal — nissan transmission assy automatic 31020 45x64Open source
17. Carpartplanet — automaticOpen source