Has there ever been a 6–5 in the Primera Argentina?

Yes, 4 times.

The first time: October 4, 1936, Gimnasia y Esgrima La Plata beat Tigre (Gimnasia y Esgrima La Plata 6–5 Tigre).

The last time: November 3, 1940, Gimnasia y Esgrima La Plata beat Platense (Gimnasia y Esgrima La Plata 6–5 Platense), 85 years ago.

Home wins: 4. Away wins: 0.

Nearby scores

1. 7–4 5 times
2. 7–5 3 times
3. 7–6 Never
4. 6–4 18 times
5. 6–5 4 times
6. 6–6 2 times
7. 5–4 37 times
8. 5–5 8 times

All games

1. November 3, 1940 Gimnasia y Esgrima La Plata 6–5 Platense
2. May 23, 1940 Racing Club 6–5 Lanús
3. April 7, 1940 Lanús 6–5 Rosario Central
4. October 4, 1936 Gimnasia y Esgrima La Plata 6–5 Tigre