TH400 3L80 Large Modulator Automatic Transmission [64-UP]

REMCO TRANSMISSION PARTS Verified independent store

→

A worn or failing modulator on a TH400 or 3L80 unit throws off shift points and can make an otherwise sound automatic transmission behave unpredictably under load. This listing cov ers a single large modulator, the specific variant used in certain TH400 and 3L80 applications built from 1964 onward, and nothing else.The modulator is a vacuum-referenced component that signals the transmission when to shift based on engine load. When it leaks or loses calibration, shifts come in too early, too late, or not at all in a consistent pattern. Swapping it out is one of the first diagnostic steps on these units for exactly that reason.This is an individual replacement part, not a kit. There are no gaskets, no seals, no filter, no bands, and no clutch components in this package. If your job calls for any of those alongside the modulator, they need to be sourced separately.The large modulator is not the only modulator variant used across the TH400 and 3L80 family. Before placing an order, verify that your specific unit takes the large modulator and not the standard size. The model code on the transmission and the production year are both useful checkpoints. REMCO has worked with automatic transmission components since 1991, and each part that ships is checked against its contents list before it leaves. A component list is packed in the box so you can confirm what arrived matches what was ordered. Weight is 1 lb. Restores proper shift timing and prevents erratic shifting caused by a failed or worn modulator on TH400 and 3L80 units. This listing covers a single modulator only. No gaskets, seals, filter, bands, clutch packs, or any other components are included with this part. The large modulator design is specific to certain TH400 and 3L80 configurations; confirm your unit uses the large modulator before purchasing to avoid a mismatch. Contents: one large modulator unit. Packaged weight is 1 lb. A component list is included in the box for verification at receiving. Before ordering, confirm the transmission model code, production year, and whether your application requires the large or standard modulator size. Show more