GM 6-Way Adjustable POWER SEAT TRANSMISSION 1979-1980 20113446 R



Cadillac Buick Chevrolet GMC Oldsmobile Pontiac 1979-1980

Our new housings are manufactured in the USA and Guaranteed for Life. The internal components are reconditioned and Guaranteed for 5 Years. These units can be installed on both the driver's seat and passenger seat. 


After installing your new unit, ship your old unit (core) to Proper Parts to receive your core refund. Your purchase receipt must be enclosed to process your refund.

Please do not ship your core until after you've finished installing the new one in order to avoid sending parts that you'll need to keep for installation. 

We ship within 1 to 2 business days.

Your core must be returned within 30 days. After 45 days, a late fee of 10% will be charged. Every 90 days after, an additional 10% will be charged.

Your core refund will be credited to your original payment method when we receive your core in acceptable condition.

What is an acceptable core?

If the outer case is broken, that is not important. The internal components are what is important. If there are missing or damaged internal components, a pro-rated refund may apply. If you have any questions, please contact us in advance. You can send photos and we'll give you a quote for the core value.

Just because your core is badly broken and in pieces, does not mean you will not receive a full core refund. We just need the internal parts.

Proper Parts has re-engineered the housings for these units.

The original transmission housings were made of nylon. They were white when new but became brown and brittle over time, and many have disintegrated. Most failures are due to the housing breaking apart. There is no new OEM replacement available for this part.


Black, Red, and Yellow Input Shaft 

The 20113446 transmissions are coupled directly to the motor through a black input shaft (or rarely white) and a black rubber coupler. The couplers are very durable but do occasionally fail. If you would like to add a coupler to your order, click the link below.

Used OEM Coupler - Part No. 20113451

Our new transmission housings are manufactured from extremely durable polyamide with fiberglass fill and are Guaranteed for Life. The internal components are reconditioned and Guaranteed for 5 Years. The complete unit is assembled, tested and shipped to you ready to be installed.

Instructions for shipping your core:

  • The purchase receipt must be enclosed.
  • Ship to: PROPER PARTS, 5725 HARRISON AVE, EXPORT PA 15632.
  • You are responsible for return shipping on your core.
  • Email tracking number to:

If you have any questions, please contact us.