Motor Mount Help

There is no need to modify engine brackets when swapping in a 318 where a 273 once sat. 273's and 318's share a common block lug lay out left and right; 340 and 360 share a common block lug lay out left and right; it is the right side block lugs that are different. They (340, 360) are narrower, and the hole pattern is different, thus the reason of having to weld on a small triangle of material and drilling a new hole, making a spacer, or stacking washers.

The MP Chassis Manual covers this information, P/N: P5249441

Hope this helps