If I'm reading your post right you plan to swap the whole S-10 chassis, frame and all. It's a little unclear to me why you need to use an S-10 front end and a blazer rear end? Maybe you have both and plan to use good parts from both to make 1 good chassis? Are the S-10 and S-10 Blazer rear ends 2 different widths? Need some more information. I didn't know there was a '49 Chebbie. P.U. involved in the equation until your last post.