Report Metalastik Coupling Sheared (6.25") in Boat Building & Maintenance Posted Thursday at 18:43 · Edited Thursday at 18:49 by bizzard Usually thrust plummer blocks have four bolts, two each side holding them down. They are also normaly fatter to contain often twin Timken taper roller bearings conically facing each other to take thrust in either direction. With grub screws through into indents in the shaft. I used to get them from BRT Bearings. Dodge Fenner type.