The LT1 is a different beast. The sbc and 4.3 brackets won't bolt up. I didn't think they would, but did a little internet browsing to be sure. After a little reading, it looks like you have a common problem. Some use Corvette accessory brackets or aftermarket brackets like March. That's an expensive option. There was also a mention of notching the frame for clearance to install into a truck, but I didn't see a year or body style mentioned.