diff's between 351C 2&4 bolt blocks

[Shawn]

I have a 4 bolt 351c in my garage that has a series of Y's cast into the lifter valley..I'm wondering if this is a trademark of the 4 bolt main block because I was in the junkyard the other day and found a cleveland with the manifold off and it had the same series of Y's in the lifter valley, however they wouldn't let me take the oil pan off to tell which block it is. Is that it, or is there any other way to tell? Email me if you can~Rurockn@aol.com

Thanks!