Some generation 1 & 2 engines, up to serial no. 3596, may require a Distributor Cap Shim 2mm P/N: 4A984A0D to be used. MTD-05-2024 should be consulted. Fitting of the 2mm shims where not required may have a detrimental effect. Skycraft only sell genuine Jabiru supplied parts. Beware of inferior pattern parts.