Based on our shop experience specializing in heavy-duty brakes since 1985:

• Bench Bleeding: Never skip bench bleeding the master cylinder assembly on a vice before mounting to the frame or booster face. Trapped air pockets inside the bores create persistent spongey pedal issues.
• Frame Alignment: Secure the frame plates precisely to the chassis rails to ensure booster rod alignment with the pedal bellcrank linkage to prevent side-loading wear.
• Fluid Compatibility: Use clean DOT 3 or DOT 4 brake fluid only.