65 66 and 67 will interchange.
1968-72
Any 1978-87 El Camino or GMC Caballero
64-65-66-67 chevelle.
A standard Chevelle frame will not fit an El Camino as it was based on the station wagon frame
No
yes it will, they are the same frames.
Yes, 1968-1972 had the same frames.
Yes
If the owner's manual doesn't tell you, you need to contact the maker.
some have coil spings some have leaf spring but will interchange
The 1980 El Camino typically fits frames designed for the General Motors G-body platform, which includes models like the Chevrolet Malibu and Pontiac Grand Prix from the same era. When looking for a replacement or aftermarket frame, ensure it is compatible with the G-body specifications. Custom frames may also be available for performance upgrades or restorations, but standard G-body frames are the most straightforward option. Always verify compatibility with the specific model year and any modifications that may have been made.
In those years they were not interchangeable.