I got to looking at my pistons,and they have the number 429 stamped on them.When I brought the truck,I was told that the engine was a 460.I have the numbers that are stamped on the block....3Y144749 on rear.......3F21T on the front.Or is the head numbers what I need to know what I have? Trying to learn! Thanks!

 

Sounds like you have the heads off....The easy way to tell is by measuring the stroke...... 3.85" for a 460 and 3.59' for a 429 Hope this helps Paul

 

It's possible for you to have either. The bore for both motor's is the same. Only way to tell is the stroke and pin height on the piston. Some people put 429 pistons in 460s because the allow for higher compression. Good luck.