I had a '85 with usd forks and disc front end which was a 600.......had a safety seat as well.
I had one of these too, 600XC. Bought it new from Bert Flood, raced it in two desert races back then, regrettably sold if for a song, as it wasnt compliance plated for rego.
Was good for 170kmh on the dirt!!!!!! Have the pics to prove it too.
Best out of the crate race ready bike I ever had. Yeah I have a soft spot for these too.
Recently seen at a swap meet recently a '88 or sightly later a LC4, first water cooled 600GS version for sale. Looked really original. I think these were Rotax also before they went to there own KTM developed LC4 version.
Had a ride on one in its day and didnt like the front end weight bias to the old air cooled one.