i'm getting frustrated(engine swapping) Putting in motor out of a '72 blazer ( a gm goodwrench 350) which was just put into the guys truck.checked the #'s and it turned out to be like a 80-90s casting. well i used to have an '81 motor in my 75 I took the 81's mounts off and then put them on the "72's" i put new bushings in the motor mounts. then i droped the engine in and the mounts are off 1/2-3/4 of an inch each side! whatd i do wrong? the mounts are clamshell type. side tabs(3/8) are near the larger opening. and the mounts will go on only one way. i dont think the block is bigger. suggestions???