I've had a 76, 78, and 79 as a Ramcharger, W150, W200 respectively. The cross members were all the same. The 440 out of the 76 Ramcharger is in my 79 now with the same mounts. The mounts have offsets on the front engine ears, with the straight part of the mount on the rear engine ears. There is more offset on the LH mount. The mounts bolt to the rear holes in the crossmember. It doesn't matter if you have a divorced or married tranfer case, as your transmission mount is in the same spot, regardless. The new mounts you have look like they may work. The one looks like there's not enough offset in it, but might be just the picture. Perhaps they don't spec the mounts for 79 and newer trucks, as they didn't come with big blocks originally?