Looks like a Weaver WA-75A or WA-75B 10 ton capacity. Visually similar to the WA-73A/B 4 ton. But 10 ton has 9" round saddle and 7" front wheels. Put a tape on it.
Manioso is correct, 4 ton Weaver. The 4 ton front wheels are below the saddle and the 10 ton wheels are way taller than the saddle. You're missing the top cover with the spec. on it. I haven't seen a triangle saddle on one until yours.
