The mounts are the same except for the second crossmember from the front (the second mounting point behind the cab). After 78 they changed in width by about three inches but are the same position along the length of the frame.
What Toyota did was change the riveted bracket on the frame. The earlier ones have the mount point (and therefore the bolt) directly above the frame rail. This makes the bolt more difficult to access. Begining in 79 they switched to an offset bracket riveted onto the top of the frame. This moved the mounting bolt outward to allow better access.