just found my numbers on block of my engine and found nice site on here to identify your motor, my numbers are 55725 4a and it measured 12" between the heads so i guess i got a small block 403, not a 350 like i was told.anyway, runs awsome anyhow ....

 

1977 Casting number for 403 should be 557265. The number you posted is missing one digit. The 4a heads are also correct for 77, they could also have been 4b.

Small blocks are all 12" between the heads at the manifold base

 

yeah after i posted my message i noticed i left out the 6, its actually 557265. but was to late to change. my motor has been painted black, but underneath some chips i see it was once blue, is that the original color? just curious.

 

Actually, you can make changes even after you press submit. Use the "Edit" feature. You're the only one who can edit your post. You can include the reason for editing if you want or leave it out. Just save the changes and the post is updated. Most of my changes are like yours, a typo or to add a picture.