97 astro distributor timing

I have a 97 astro van 4.3 engine. I think the distributor is not timed with the camshaft. On the balancer is the 1st or 2nd mark TDC?? There is no way to time the engine as the dist will not turn. I think the dist is off 1 tooth on the cam.

I have to replace the dist cap and rotor ever 2000 mi. It will start missing soon after replacment. I've replaced the spark plugs twice, the spark wires twice and Camshaft senser.