Fleece Performance Engineering Internal 20‑Pin Wire Harness Connector Seal — Black 1‑Pack, Includes O‑Ring & Connector

A direct-fit 20-pin internal wiring harness seal that replaces worn OE seals to stop oil intrusion in Allison LCT1000/LCT2000 and GM 4T65-E connectors.

When an automatic transmission harness seal fails it can allow oil into the connector, causing corrosion, electrical issues, and intermittent faults. Fleece Performance Engineering supplies a complete replacement kit that restores a clean, dry connection: a new 20-pin internal seal sized for the OE harness, a replacement O-ring for the connector body, and a fresh connector shell. This kit is intended as a straightforward repair part for technicians and DIYers servicing Allison LCT1000 (2001–2019), LCT2000, and GM 4T65-E transmissions.

How does this seal stop oil getting into the transmission harness?

The seal forms a barrier around each of the 20 internal terminals and mates with the connector body O-ring to prevent fluid migration into the electrical cavity. Properly seated, it restores the original moisture- and oil-resistant path.

• 20-pin internal seal matches OE dimensions for tight fit
• Includes connector-body O-ring to renew the mating surface
• New connector body replaces cracked or deformed shells
• Black elastomer resists oil and aging under normal operating temperatures

Will this fit my Allison LCT or GM 4T65-E harness?

Yes — the part is designed for internal OE-style harnesses used on Allison LCT1000 (2001–2019), LCT2000, and GM 4T65-E transmissions. It replaces several hard-to-find original seals and fits harnesses listed by the OE part numbers.

• Compatible with Allison LCT1000 (2001–2019) and LCT2000
• Engineered for GM 4T65-E transmission harnesses
• Direct substitute for OE internal seals P/Ns: 29545307, 29541371, 29539792, 29543336
• Sold as a single 1-pack kit for one connector repair

What does the kit include and how easy is installation?

The kit bundles the internal 20-pin seal, a replacement connector body, and the mating O-ring so you can complete a repair in a single service procedure. Installation requires basic terminal release tools and careful seating of the seal to ensure the correct compression with the connector body.

• Included: 20-pin internal seal, connector body, and connector O-ring
• Installation needs terminal removal/retention tools and clean mating surfaces
• Follow harness terminal orientation and index tabs when reassembling
• Recommended inspection of pins and wiring for corrosion or damage

How long can I expect the repair to last and what should I check?

When installed correctly and used under normal operating conditions, the replacement seal and O-ring restore the original sealing function and should last through routine vehicle service intervals. Periodic inspection is advised after heavy use or fluid exposure.

• Material resists oil and typical underhood temperatures
• Inspect for oil residue, pin corrosion, and O-ring compression during service
• Replace immediately if connector body is cracked or pins are damaged
• Keep connector and cavity clean before reassembly for best sealing

Who this is for: technicians, fleet maintenance teams, and experienced DIY mechanics who need an OEM-compatible internal connector seal for Allison LCT1000/LCT2000 or GM 4T65-E transmissions. If you’re replacing a hard-to-find OE internal seal or repairing a connector that has oil intrusion, this Fleece Performance Engineering one-pack kit gives the parts required to restore a sealed, reliable electrical connection.