The original connecting rod beam (forging ID C9OE-A) featured drilled oil squirt bosses to lubricate the piston pin and cylinder bore and rectangular-head rod bolts mounted on broached shoulders. A number of fatigue failures were attributed to the machining of the part, so the bolt head area was spot-faced to retain metal in the critical area, requiring the use of 'football head' bolts. In 1975, the beam forging (D6OE-AA) was updated with more metal in the bolt-head area. The oil squirt bosses were drilled for use in export engines, where the quality of accessible lubricants was questionable. The rod cap forging remained the same on both units (part ID C9OE-A). In 1982, the design of the Essex V6 engine used a new version of the 351W connecting rod (E2AE-A), the difference between the two parts was that the V6 and V8 units were machined in metric and SAE units, respectively. The cap featured a longer boss for balancing than the original design.