And the main difference between the 240 and 241, and also the 264 and 265, is that the 240 and 264 are straight-valve engines, while the 241 and 265 are tilt-valve engines. Many of the parts are identical between the 240 and 241, and between the 264 and 265, except the heads are different, as are the head gaskets, pistons, and valves. If you look in the Federal-Mogul engine parts book, they list many of the same parts. They specify that the person ordering measure the head width to ID properly. The 282 and 308 were part of the Blue Diamond (BLD) family along with the 269. Later on they were also known as the Black Diamond (BD). The 220 was known as the Silver Diamond (SD). The 240 and 264 were also called Black Diamonds, but later became the 241 and 265 and were called the Blue-Greens or Blue-Greys (BG). (Color was actually Detroit Diesel green-grey.) I think the main difference was what color they were painted new and the year they were made. If you visit the OldIHC database and punch in the engine numbers, you will see many different entries repeating this. Forget I brought up the 308. I thought it was in the same family as the SD and BG engines. I would think that a person could juggle blocks, heads, cranks, rods, and pistons and build a larger engine. You have many different blocks, and at least one good tilt-valve head. Mix & match. I am going to the library to look up the specs on each.