|These high quality exhaust studs are produced from cad plated steel in 5/16 x 18 standard thread size and length is 1.5" and are a direct replacement for the Lycoming part number 31C12 stud. These studs DO NOT feature a safety wire hole (refer to p/n 08-06780 for safety wire hole feature). FAA approved for all Lycoming engines from 0-235 through 0-540.|
No question on the high quality of this stud. Although when I installed, some studs were too short to install washers. I wish they offered a stud 0.24 longer.