TH125 3T40 [80-25] Automatic Transmission Filter C Kit with Pan Gasket

When a 3T40 unit comes in for a pan-drop service, having the correct pan gasket and a fresh Automatic Transmission Filter ready together saves a second parts run and keeps the job moving. This two-piece set pairs a duraprene bottom pan gasket cut to the TH-125 pan profile with an Automatic Transmission Filter sized for the 125 and 125C applications, covering 3T40 units built from 1980 forward.

The duraprene material on the pan gasket compresses with consistent pressure across the entire pan rail. That even compression matters because an uneven seal on a 3T40 is one of the quieter leak sources: the unit may not puddle on the floor but it seeps enough over miles to drop fluid level and eventually trigger soft or delayed shifts. Replacing the Automatic Transmission Filter at the same time removes the restriction that builds up in a clogged element and restores proper fluid pickup to the valve body.

This is a focused two-piece set, not a full overhaul kit. It does not include friction plates, steel plates, sealing rings, bands, or any other internal components. Technicians doing a complete rebuild will need to source those parts separately. This set is specifically for a pan-drop and Automatic Transmission Filter service on an automatic transmission that is otherwise mechanically sound.

Each set is assembled at REMCO, with both pieces pulled and checked individually against the parts list before the box is sealed. The printed parts list ships inside the box so you can verify contents on the bench before the car goes on the lift. REMCO has been working in automatic transmissions since 1991, and this kind of single-job set reflects how the shop actually works: two parts, one service, nothing missing.

Confirm the unit code reads 3T40, cross-reference the TH-125 designation if needed, and verify the build year is 1980 or later before placing the order.

• Sealing the bottom pan correctly stops fluid leaks at the pan rail and keeps the unit from losing pressure over time, which is one of the first causes of shift complaints in 3T40 units.
• This set does NOT include friction discs, steel plates, sealing rings, bands, bushings, solenoids, or a full overhaul gasket set. If your job needs those parts, check your parts list before ordering.
• The duraprene pan gasket is cut for the 3T40 bottom pan profile and compresses evenly along the rail, reducing the risk of uneven seating that causes seeping leaks after a service.
• Contents: 1 TH125 bottom pan duraprene gasket and 1 Automatic Transmission Filter for 125/125C applications. Total kit weight: 1 lb. Both pieces ship together in one box with a printed parts list inside.
• Before ordering, confirm the transmission code on the unit is 3T40 (also referenced as TH-125) and that the build year falls within the 1980-and-up range this set covers.

What's in the box

• 1 x Automatic Transmission Filter, 125 125C
• 1 x Pan Gasket, TH125 Bottom Pan Duraprene

Compatible vehicles

• Fits Century [82-84], Skylark [80-84], Cimarron [82-84], Cavalier [82-84], Celebrity [82-84], Cutlass Ciera [82-84], Firenza [82-84], 6000 [82-84], Fiero [84], Phoenix [80-84], Sunbird / 2000 [80-84], Skyhawk [82-89].