Universal Alternator Cradles - Builder Series - GM 12SILaser cut 1 4" mild steel brackets make a great starting point for customers who are adapting alternators to custom applications. WELDING IS REQUIRED, recommended for experienced fabricators only. This bracket kit fits all 7127 series MechMan alternators for 1963 1985 GM applications, as well as all GM 10DN, 10SI, and 12SI GM alternators with 6. 61 inch center to center bolt patterns. Mockup front alternator housing and hardware is included.