Engine work is unforgiving about dimensions, so this category leans heavily on measured specifications: bore size, journal diameter, seal inside and outside diameter, gasket thickness and bolt hole count. Where a part is available in oversize or undersize, the size is in the product title.
Multi-layer steel head gaskets list compressed thickness. Bearings list the undersize increment. If you are rebuilding rather than repairing, check the clearance specs against your machinist's measurements before you commit.
