Mustang II suspensions are comparable to the Chevy small-block or Ford 9" rear-end in the car world; tough, time tested and universal. These suspensions may not be the most advanced design on the planet, but it is perhaps their very simplicity that makes them so popular. A number of companies make Mustang II-based suspensions for practically any car including, of course, the Mustang II (1973-1978) itself.
Part of the M2's suspension popularity rests on the fact that it can be installed as a self-contained unit, and does not rely on any external parts to mount the springs or shocks. Most suspension kits come with a new cross-member, upper suspension mount "hats," upper and lower control arms, strut rod brackets, steering knuckles, mounting hole template and (theoretically) all nuts and bolts required to put everything together.
Because the engine mounts to the cross-member, you're going to have to remove it first. Remove all of the old suspension components and their associated brackets and toss them in the scrap heap. Before removing the old cross-member, weld a length of thick 4-inch C-channel to the front of your frame horns to act as a temporary cross-member. Mark the location of your radiator core support before removing it. Vehicles that have C-channel frames will need the open portion "boxed in" to at least 4 inches on either side of where the new cross-member will go, but you might as well box the entire frame while you're at it.
Owners of Mustang IIs can use the original cross-member, and will not need to remove the engine. But new cross-members are lighter, stiffer and better, so consider replacing it anyway.
Use the template provided with your kit to locate the holes you'll need to drill. This step is crucial; misalignment of the template will result in a crooked suspension, so take your time when clamping it and center-punching your holes. Follow the directions that come with your kit. Different frames and suspension suppliers will require different mounting locations.
Do the same thing with the spring "hats" on top of the frame. Once everything is bolted together, you could leave it that way, but a few spot welds would be helpful.
Mount the steering box assembly onto the cross-member, and bold your control arms to the mounts. Install the shocks, springs, sway-bar and steering knuckles as per your kit instructions. You can't use too much grease on suspension components, so don't be stingy.
Wait until you get the engine installed to link the steering column to the box. You may need to re-route it depending on your original steering configuration and the headers used.
