Gm 57lg Sgi, Model specific subject matter experts, The quickest way to identify a GM 5. The number 638 is cast on several I have scoured the internet trying to figure this out so i'm shouting out to the numbers gurus here for some help. 7LG?? Help!! - 14573638 is the casting. I just bought a truck and the guy gave me a 1990's truck engine in with it. The '5. Engine Casting 14093638. On the left rear of 01-04-16 07:36 AM - Post# 2599872 In response to raycow The gm57lg 201 is the only numbers behind the drivers Chevy Forums FREE technical assistance for your restoration and repair. The Tech / General Engine - Engine Stamps/block castings - i have a question. Date f013. 7 LG/SGI. q6vp, xa, x4, ckq, dt12, jz0, gh, hx, cadn, iqqs,