Those holes are for side engine mounts when the block is paired up with a Powerglide transmission in a passenger car. The PG had a rear mount that fit on a crossmember atr the rear of the transmission, and no bellhousing mounts like a 3-speed standard transmission. Hanging the engine/trans assembly by front and rear put too much stress on the bellhousing, so the front mount was moved to a mid-engine position. I'm restoring a 51 2-door hardtop with that mount setup right now.
Jerry

Last edited by Hotrod Lincoln; 12/06/2008 3:11 AM.
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