I'm gearing up to add two rows of 4" louvers to my '63 c10 hood. The source I've found will mail you the rows of blanks in 2", 3" or 4" louvers for you to weld in. Fergie Rodine is the name. Email your request to: [email protected] Prices are cheap! $1.50 per louver plus the sheet metal cost and shipping. I can't wait to punch that hood!