How do I check if my engine is the original? I think my old engine is the original, but the last owner said it was not. The last owner said the engine was a rebuilt 351m, but that is only what the owner before him said, and the engine turned out to be a 400. However, it could be a mildly rebuilt 400, because my dad just put a reman 400 in an identical truck and my 400 was faster and with at least 80,000 miles. The hood sticker says it is a 400. Any help would be appreciated. Thanks.

Wanted: Winch for pulling out Chevys!

79 F150 4x4 410m Built Ford Tough!(9.1:1,KB pistons,custom Comp Cams X-Treme 210/218-.508/.524,roller rockers)/c6/3.5:1 gears,4.11:1 soon, Demon 4bbl, 285/75R16 BFG Mudders on alumn. mags with New Drk. Blue paint.
65 Ranchero 170-6, 3on the tree, solid mags, New Bright Yellow paint

 

You can pull the starter and check the date code cast into the block above it. There may either be a sticker with a date code on one valve cover or a tag bolted to the intake manifold somewhere with codes. The code will look something like '8E11' with the number/letter combination depending on when the truck was built. (year/month/day). Compare these with the date on the door frame sticker.