Lakewood ScatterShield Blockplate ID #15781

[pntastar69]

What is the difference between these Lakewood Scattershield Blockplates? Both are for a small block 833, one has vents, the other doesn't. Both are stamped #15781. Does it make a difference on which one to use?

I also noticed that there are 4 captivated nuts at the top on one but not on the other.

 

[Daves69]

Might be totally off with this. I tend to believe the vented is more track oriented. Constant use on the street and road driving may allow pickup of more dirt. So I guess it depends on the intended use.
The welded nuts are a nice convenience.

 

[DDodger]

might be as simple as manufacturing dates, like the bm weighted flex plates