If the manufacturer says it's .039" they probably know. If they are wrong and it's .002" thicker....I don't think the sky will come falling down. I agree. I used those same gaskets on my 440. I was able to get .042 worth of feeler gauges between the head and block with that gasket torqued to spec. Close enough for me.
'68 Coronet 500 w/ Indy EZ-1 headed 446, 727 trans, 9" rear
First day at the track with SUV street tires and no traction: 1.688 60', 7.24 @ 101.79 in the 1/8 mile
Great customer service from: DominicThumper Carbs, B3 racing engines, Porter Racing Engines, A-1 torque converter's, Quick Performance, Racer Brown Cams, R&R Performance, Manton pushrods
| 
