Quote Originally Posted by chevy427tall
picked up a 350 chevy 4 bolt block 3970010,cast and assebled in 1975, was reading up on chevy small blocks, it said the samll blocks with high nickel content had a 10 or a 20 cast into the block under the timing chain cover, on my block there is a 020 cast into it but there is 4 or 5 other numbers cast right above it, just wanted to know if it was a high nickel content block or not, i read they stopped doing that after 1973, but that was in a small block mopar book.

thanks
Russ
Most of the "higher nickel" blocks that I have found came in 68 to 72 Chevy and GMC trucks.
These early blocks where also a little heavier in weight compared to the blocks made in the middle and late 70's
If you look at the area around the bell housing where the bell housing bolts go in to the block on some there is a lot of material missing.
If you use these 4-bolt blocks I would try and keep the hp less than 550.