1. The Transmission and Related Components:
* Automatic Transmission: You'll need a used automatic transmission compatible with your truck's engine and year. Finding one from a similar year and model Chevy truck is your best bet for ease of installation. The transmission must be in good working condition. Consider a professional inspection before purchase.
* Torque Converter: This connects the engine to the transmission. It's specific to the transmission you choose and absolutely necessary.
* Transmission Crossmember: The manual transmission's crossmember won't work with the automatic. You'll need one designed for an automatic transmission of the same type you're installing.
* Driveshaft: The length of the driveshaft is often different between manual and automatic transmissions. You might need a shorter one or have yours modified. This is critical to avoid vibrations and potential damage.
* Transmission Mount: This secures the transmission to the frame. It's specific to the automatic transmission and will differ from the manual mount.
* Shift Linkage/Control Cable: This is how you'll shift the automatic transmission. You'll need the correct linkage or cable (depending on the automatic transmission type) and potentially brackets or adaptors.
* Fluid Cooler Lines: An automatic transmission needs a fluid cooler; these lines route transmission fluid through the radiator for cooling. You'll need the lines and maybe adaptors.
* Transmission Control Module (TCM) / Computer: Depending on the year and model, your truck may require a TCM to control the automatic transmission's shift points and other functions. If the truck originally had a manual transmission and no TCM, you'll potentially need it and the required wiring.
2. Other Necessary Parts and Supplies:
* New Transmission Fluid: Use the correct type and quantity specified for your new transmission.
* Gaskets and Seals: Many gaskets and seals will be needed for the transmission and related components. Plan on replacing them all, as reusing old ones can lead to leaks.
* Bolts and Nuts: You'll likely need various bolts and nuts to secure the transmission and its components.
* Wiring Harness (Possibly): As mentioned, depending on your specific setup, you may need to add a wiring harness to accommodate the TCM.
* Mechanic's Tools: A wide range of tools are required, from basic hand tools to specialty sockets and possibly transmission jacks.
3. Considerations:
* Professional Installation: This is a significant job that requires mechanical expertise. Unless you have extensive experience with transmission swaps, having a professional mechanic perform the work is highly recommended.
* Computer Programming (Possibly): If a TCM and computer are required, programming might be necessary.
* Exhaust System Modification: The automatic transmission's location might interfere with the exhaust system. You may need to modify the exhaust pipes or hangers.
* Clutch Pedal Removal: You will need to remove the clutch pedal assembly.
This list is not exhaustive but gives you a good idea of the complexity involved. Before starting, consult a repair manual specific to your 1990 Chevy truck and the automatic transmission you intend to install. The manual will provide detailed instructions, torque specifications, and wiring diagrams. The cost of the parts and labor could easily exceed $2000, depending on the transmission choice and labor rates in your area.
