Well, I got curious today and decided to tear into my 350. Here's what I found. 1. Rust on the cylinder walls. I know this is my fault for letting the truck sit for a while without a hood or an air cleaner on it. 2. Cylinders have been bored .040 over. 3. It's a 1-piece rear main seal with 4 bolt mains. Now for my questions. Will I be able to have the rust honed out, or will it have to be bored even more? I ask this because I don't really want to take it to .060 over to drive on every day and tow with. What did 4 bolt main, 1 piece rear main sealed engines come in? I pulled this engine out of my K5 and I'm just curious what it could have come from. It's obviously a remanufactured engine, given the tag on the side of the engine. WILL I BE ABLE TO USE THIS BLOCK AND IS IT WORTH A FLIP?!?!