I know my question is not thridgen related but can someone please help he me anyway. I know there's alot of you guy running 305s and here's delima I have at the monent.

I'm working on installing a 87 montie carlo 305 into my full size 88 GMC truck. The guy I got the engine from had removed the harmonic dampner from it and forgot to give it to me when I got the engine. Here's my question why did GM use 2 different thickness dampners on their 305's and are they compatable? The one that came on the engine was 2 1/2" thick but my truck has a 3/4" thick dampner and would like to know if I can use it. I know the 305's are internally balanced.

Thanks,

 

Are the diameters the same?

 

yes they are but the timing tabs in a different location but i do however have the matching timing cover and tab from the truck as well.

 

Any of the balancers (except from a 400) will interchange across any of the engines (except the 400) as long as you're mindful of the differences in diameter and timing mark location.