This shop is famous for their crab bee hoon / noodle soup. The dish is very much like fish head bee hoon except that it’s crab they use instead of fish. The crabs will set you back about S$40 per kg.
They have spun off a branch in Ang Mo Kio Block 233 (opposite the current one) called Uncle Leong’s Seafood (apparently opened by a disciple but not as good as this one). Again, don’t be deterred by the long queue.