I Have a 90 YJ with a 4.2. The frame is pretty well rotted. I know there are frame pieces you can buy but I found a frame on Craigslist for $200 that they claim is in perfect shape. The only problem is that it is for a 4cyl. I've read that the only difference is the placement of the engine mounts. Is this true or am I gonna run into a world of problems? Most people tell me to get rid of it but like most of you, I love my jeep. I know this isn't gonna be an easy task but is it worth swapping out a frame. Any insight or tips on what to expect will be greatly appreciated. Thanks to all who reply.