The crankshaft vibration dampener bolt is 3/4"-16 UNF, 2.3 inches long, with a 1.5 inches minimum length threaded area.
You will also need a thick washer, the washer is 1-15/16" x 1/4".

summitracing.com: part number DCC-5249557AB

Mopar Performance #P5249557AB - Mopar Performance Harmonic Balancer Bolts 3/4-16 x 2.250 inch (underhead)

Or just get one from an old V8.

Olaf.

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Aspenized

a Lisle brand puller has the jack screw the same thread and pitch as the /6, 3/4-16! Its big, beefy and more importanty, can be used to INSTALL the damperr too! You just need to buy a grade 5-8 matching nut for the jack screw. Install damper as far as it will go on, thread jack screw into snout and snug it finger tight (at least 8 threads) put washer and thread nut on and run it down to balancer. Use 9/16 wrench to hold jack screw hex end stationary while using a 1 1/8 open end or crescent to turn big nut. Use some grease on the threads to prevent galling. The damper will push right on (about another inch!) without the crank turning. if you can get 135 ft/lbs onto that bad boy with a crescent, your better than me! To remove installer, just back off nut slightly and it should unthread by hand. Works with V8's too, but finish off with a crank bolt at 135 lbs.

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I didn' t buy it, I built it.....