I had left a few holes unriveted while I determined whether to use regular or pulled rivets in the tight locations on the rudder. After consulting with Van's I elected to substitute the AN426AD3-3.5 rivets for MK-319BS rivets in the narrowest parts of the trailing edsge of the upper and lower rudder ribs. Having completed it, I'm glad that I did. It was a lot less of a hassle than attmepting to rivet them.