Here is a water jacket for 1927-1930 Auburn 77, 88, 90, and 95, as well as pre-1933 Lycoming GU and GG. This is about 28 1/4 inches long overall with 27 5/8 inch C-C for end bolt holes and 3 3/4 inches C-C across the width. 34 bolt holes around the sides, 1 1/2 inch OD tube coming out on about a 45 degree angle. Be sure to check my other listings.