Pretty easy because there was no El Camino SS in 1978.
Doors from a 1978-87 El Camino or GMC Caballero
Any 1978-87 El Camino or GMC Caballero
187 inches
From 1978-1987
The back glass from any 1978 or newer El Camino or Caballero will work.
You can only tell if the El Camino is a Royal Knight by the build sheet, the VIN number will not tell you. If you do not have the build sheet then there is no other way in telling. I have one and it is the only way I could tell if mine is a true Royal Knight.
Yes
Yes
The model is a 1978
Only as an option.
probably a th350.
Same as a 78 chevelle.