Just for comparison, here's a pic [pinched from a recent FleaBay ad] of what I reckon to be a definite SA built 520:
[Linked Image]

Distinguishing points: Handle locking setup; deck, height adjuster and discharge flap design are typical '70s SB, not Rover. Decal style and placement, ditto. Seller quotes the model number as 520129, as well, which is correct for the 1978 era.

Cheers,
Gadge

"ODK Mods can explain it to you, but they can't understand it for you..."

"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."