TSP Resleeved Aluminum Gen 4 Engine Block, Outright**Power Bore Sleeves are not available below 4. 07" bore size** Texas Speed & Performance is proud to offer our Gen 4 resleeved aluminum GM engine block using state of the art, American made dry sleeves! We are machining and installing Power Bore and Darton sleeves at our facility using new GM Gen 4 aluminum blocks using only the best CNC equipment available. Both sleeve brands have steps in them to alleviate the possibility of ever "dropping" a