The 240 and d21 engines are not as alike as you might think. I just put a sohc 240 engine in my hardbody. I thought the block and head should be the same. WRONG!! The 240 engine has alot more webbing on the back of the block which makes the truck starter not fit. The 240 engine has a main girdle which makes the truck oil pan not fit not to mention the dipstick is in the wrong place and will not fit. The truck engine mounts will bolt to the 240 block but they sit 3/4 of an inch more forward than the truck block. No problem but you have to make a tranny mount because the engine mounts now shifts everything forward. ETC.. ETC..