I recently purchased a 1953 F350 Tow truck.  It has a "Y" block in it.  I have no idea what size it is or if the truck originally had a flathead and this engine was installed later.   The guy I bought it from said hat he was told that some 53 commercial trucks actually came with a "Y" block.  The VIN in this says it should have a flathead.  Any body have any ideas how I can find out what my engine is?  Thanks 

Tim

Tim