Fence post repairs

Hi
I've got 3no fence posts to renew as they have rotted at the base. They are 3" x 4" in size. The fence is on a sloping site and it will be difficult/impossible to take out the concrete.
Have been considering metpost repair spurs. They do a 3" and 4" both square but not a 3" x4"!
I could use the 4" sq type and pack out one side or a 3" sq and cut out 1" slice at the base of the post so it fits.
Any advice/thoughts appreciated.

I'd try my very best to drill out the remaining post ends from the concrete.....you will get there (eventually) by using a long auger drill and a chisel.
I don't rate Metposts very much.
John

take along a Henry vac, discard the chrome bend, pipe straight in the hose.Length of round plastic conduit to prod out the inevitable blockages. No bag.As Burnerman said, long auger and chisel, and suck out the wood flakes.

hire a kango breaker for a day to take out the concrete, it will slice through the concrete like butter.

i second not liking metposts, just another thing to go wrong