153 or 168 tooth flywheel?

[327power]

Which one do I need for my truck? I am buying a 350 V8 and will have a 4 speed behind it. It's got a 3 speed at the moment.
I would go check what it's got now, but I'm kinda in Iraq for another month. Does it even matter what size flywheel I use, besides the fact that the starter might be screwed up?(from not contacting the teeth on the ring gear.) Thanks.

[Lt.Del]

i think you have a 168.  I know I do.  I could be wrong, but, I think 305's may have the 153.   Do you have the staggered bolt holes on the starter?  Or are they paralell to the end of the block. 

I have staggered bolt holes on my starter and have 168 tooth.  I think you can tell that way.

[Irish_Alley]

from what i can tell the 168 is a bigger fly wheel the od is 14.23" and the 153 is 12.85 which is only 1.3" difference but wow that mean if you get the wrong one it just will not fit the 168 seams to be more popular i would go with that one