I'm trying to figure out exactly what engine this is. It is a BB with engine casting # 3855961. near  as I can tell it is either a 396 or a 427 by going off of the casting. The ID # is T0428LB, the date code is D215, and stamped on the front of the block is PASS HI PERF 3, aslo the vin is j252798 or 0252798. If anyone is able to help me further ID this it would be greatly appreciated. Thank you.  

Keeping in mind that your casting number is not exclusive to just one application. Your "LB" suffix narrows it down, but it was used on more than one engine. According to the info that I have, the casting number and the suffix only pair up on one engine. That would be a 1965 396 passenger car with a powerglide, 325 HP, two bolt main.  

Thank you very much. That helps me out alot. By the way, do you have any idea what this block might be worth? I am thinking about selling it. Thanks again!!!