Whether even- or odd-fire, the Buick V-6 is a natural choice for smaller 4x4s and early Jeeps. The dead giveaway is the front-mounted distributor. This is a rare late-model 231 odd-fire. The earlier 225 odd-fire from ’63-’74 and the 231 odd-fire from ’74-’75 are more highly sought after, however you can use their 50-pound flywheels on the ’77-’82 even-fire engines if you have them balanced to the crankshaft. The quickest way to tell the difference is to check the distributor caps if they’re still there. The odd-fire engines will have two dummy plug wire towers at 2 and 6 o’clock, while the even-fire will not.