Early 360 blocks

Well I'm not sure if that's exactly the proper way to say it but the very first 360's were thick wall castings. They were basically 340's blocks that were's bored out as much but they have larger mains than 340's. There's alot of controversy about when the 360 thick wall castings ended. I used to hear they ran all the way through 72 but recently I've heard reputable engine builders say they have sonic tested blocks and found even 72 360 blocks weren't thick wall so your best bet if your looking for a thick wall 360 is to get a real early one and keep your fingers crossed and have it sonic tested before you bore it out.

Incedentally sonic testing should be done on any engine before boring it over .020 in my opinion.