the 31 , sure looks like a 81 to me too...plus the picture with head number says "firing order" on it...and the second 8 is most likely a 6.....those would be the cylinders.....I do not know the firing order ,but it sounds about right? head number should be on the center port....like a 16, 6X, 7K3 or 5C or such, a two or three digit number and/or letter combo
