Yup, you need those pins otherwise it won't be exactly centered and will vibrate. I had a vibration develop on my 289, it was worst at right about 3000rpm, and when I started checking stuff out, it turned out some of my pressure plate bolts had loosened up about 1/2 turn, and it actually caused the tip of one of those dowels to break off. I lucked out and just tighening up the bolts along with the 2 remaining pins the vibration went away, but in your case you need to have SOMETHING to locate it in the exact right spot.

BTW, you can get dowel pins that are machined down on half of the pin, for the situation like you had where the holes were too small. It's a Ford part, I can get you the part# when I get home if yo need it.

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'86 Bronco, 460, E4OD; '85 Ranger, 350hp 289, T5, 12.9@110.5
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