i have a copy of a 337 approved on 9-18-92 on N2617H serial #3242, a 415-d. it's for the installation of a steel bushing (spacer) between the top "donut" and the existing stop on the main landing gear . the paperwork claims it's necessary on aircraft with dual fork nose gear in order to get the correct tail hight. the deminsions are as follows: thickness 7/16", outside diameter 1-5/8" inside diameter 1-1/8"
hope this helps, bernie
