12520270 -5.7L 350CID (LO5-K) 1987-1995 Chevy & GMC Full Size Trucks & "G" Van & 1996-2002 "P" Van - Over 8,600 GVW

It uses the 14102191 heads which have a 76cc chamber
Specs
1986 and up 4 bolt main 1 piece crankshaft seal block(no mechanical fuel pump provision)Nodular iron crankshaft
Powdered metal connection rods
Dished hypereutectic pistons
8.75:1 Compression ratio
High volume oil pump
Morse link type timing chain


12568758 - 5.7L 350CID (LO5-K) 1987-1995 Chevy & GMC Full Size Trucks & "G" Van-Up to 7,200 GVW- Uses 14102193 heads with the 65.3cc chambers
Specs on this engine are as follows:

  • 1986 and up 2 bolt main 1 piece crankshaft seal block(no mechanical fuel pump provision)
  • Nodular iron crankshaft
  • Powdered metal connection rods
  • Dished hypereutectic pistons
  • 9.25:1 Compression ratio
  • High volume oil pump
  • Morse link type timing chain


Not sure if that info is correct,its from PAce Performance.
peace
Hog