What frame could you use to convert a 1986 Chevy El Camino 4x4 vehicle?

There's no such thing as a factory 1986 Chevy El Camino 4x4. The El Camino was a rear-wheel-drive vehicle. To convert it to 4x4, you'd need a completely custom frame. There's no readily available frame that would be a simple bolt-on solution.

You'd likely need to fabricate a custom frame, potentially starting with a frame from a 4x4 truck of a similar vintage (like a Chevy Silverado or GMC Sierra) and heavily modifying it to fit the El Camino's body. This is a very extensive and complex project, requiring significant fabrication skills and welding expertise.

Factors to consider when choosing a donor frame (or designing a custom one):

* Wheelbase: The El Camino's wheelbase is significantly shorter than most 4x4 trucks. You'd need to shorten the frame or find a frame with a comparable wheelbase.

* Suspension: The chosen frame would need to have a suspension system compatible with 4x4 components (transfer case, differentials, axles).

* Engine and Transmission: You'll likely need to adapt the engine and transmission mounts to the new frame.

* Steering: The steering system will need to be adapted to the new frame geometry.

In short, there isn't a "plug and play" frame. Building a 4x4 El Camino is a major undertaking, better suited for experienced fabricators and off-road vehicle builders.