'37-'39 Chevy Pickup Mustang II Crossmember

1.	The first step is to put the vehicle up on jack stands. The truck should be sifting at about the same angle as it usually does when on the ground or slightly lower in front.
2.	The next step is to remove the old suspension system completely. The front shackle mounts riveted in the factory location are used for a reference point. Be sure to flatten the top of the frame rail where it is turned up for the factory steering box mount.
3.	Part of the radiator support crossmember will need to be removed. Only remove the portion indicated (see Figure A). This section needs to be removed to provide clearance for the rack and pinion steering unit. Leave the front part of the crossmember in place to support the radiator.
4.	Using the provided boxing plates you will need to box the front section of the frame rails where the crossmember will be installed. Position the plates starting at the rear of the modified radiator crossmember. You may grind the inside edges of the frame rails flat so that the plates lay flat against them, but be careful not to grind off too much or the frame rails will be too thin in that area. The boxing plates can set on the lower flanges of the rails in front, but most of the flange will later be cut away for the C-notch for the rack and pinion unit and the crossmember clearance. Fit the plates, weld and grind smooth.
5.	The next step is to install the new crossmember. Measure straight back 17-1/4" from the center of the front spring shackle hole in the frame and make a vertical line (see Figure B). This will be the center line of crossmember and the spindles. Position the crossmember up between the frame rails centered on the line you made. If the crossmember does not fit between the frame rails you may grind the edges of the crossmember uprights to help it fit better. Be sure that the crossmember is all the way up and that the horizontal edges are seated against the underside of the frame rail. Tack weld the crossmember in place once you have it property positioned.
6.	The upper spring hats should be installed next. The spring hats should be positioned on top of the frame rail 1-3/4" forward from the front face of the crossmember (see Figure C). The taller side of the spring hat goes toward the front of the vehicle. You may grind the spring hats if they do not sit flat against the top of the frame rail. Tack weld the spring hats once you have them properly positioned.
7.	The next step is the C-notch for clearance for the rack and pinion unit. If using a manual rack & pinion unit, measure forward 4-5/8" from the centerline of the crossmember and up 1-1/2" from the bottom of the frame rail and make a mark. Draw a 2-1/8" radius with your mark at the top of the radius (see Figure D). If using a power rack & pinion unit, measure forward 5-3/8" from the centerline of the crossmember and up 1-1/2" from the bottom of the frame rail and make a mark. Draw a 2-1/8" radius with your mark at the top of the radius (see Figure E).Trim out the material marked, leaving about 1/8" to work with, and then install the rack and pinion unit and see how the clearance is with the C-notch filler pieces. Finish grind the notch for fit and location, and then tack the filler pieces in place. You may now remove the rack and pinion unit.
We do not recommend using strut rods. Tubular control arms distribute brake load much better. However, if you choose to use strut rods, use the instructions in step 8.
8.	The lower control arms and strut rods can be used for locating the strut rod plates and gussets. Using a piece of wood and a C-clamp install the lower control arms as shown (see Figure D). Install the strut rods onto the lower control arms and assemble the rear strut rod ends with the large rubber bushings, cup washers, and including the strut rod plates. Align the tops of the plates with the undersides of the frame rails, then fully tighten the nuts on the strut rods to their fully seated position (see Figure F). The strut rods will act as alignment fixtures while you tack weld the plates in place, then tack weld the support gussets as well (see Figure G). You may now remove the strut rods and control arms.
9.	You may now finish weld all of the parts in place. M. I. G. welding works best for this, but any kind of properly done arc welding will be good. Weld the crossmember and spring hats all the way around. The spring hats can also be welded on the inside on the sides of the frame rails. Weld all the way around the strut plates and gussets. Weld all around the C-notch filler pieces also.
Set ride height so that the lower control arms are horizontal to the ground and align the wheel with the following specifications:
	Camber: 0º Caster: 1-1/2º positive      Toe-in: 1/16" for radial tires, 1/8" for bias ply tires
Please note: It may take 100 miles or more of driving for the truck to settle to ride height. The truck may settle from ¾" to 1".