"INTERNATIONAL HARVESTER DIESEL ENGINES
6.9L and 7.3L Core Identification
6.9L Old Style Block
Block Casting Number:
On left side of block (beneath oil cooler) 1805440C1
Note: Some 440 blocks are truly new style and must be visually inspected by raised donut around the block heater, frost plug (right rear). Old style below serial number 173828.
*No counter bored area for block heater
*No defined area on side of block for dip stick
*Thickness of cast iron around block heater 3/8" (.375")
*7/16, 12 point socket is used to torque head bolts
*Block tapped with 7/16-14 for head bolts
6.9L New Style Block
Block Casting Number: 1807996C1 Note: Some new style blocks have casting
number 440. Above serial number 173828.
*Has counterbored area for block heater
*Very defined relief area cast in side of block for dip stick tube.
*Thickness of cast iron around block heater 15/32" (.470")
*Latest style (not all new style 6.9) has ribs around head bolts, rear two on left side go from head gasket surface to pan rail - same as 7.3
*Same as old style 6.9
Block Casting Number: 1809000 C1
Visual Identification: *Same as 6.9L new style block
*Head bolt ribs on side of block extend from pan rail to head gasket surface or rear two head bolts left side
*1/2" - 12 point socket is used to torque head bolts
*Block tapped with 1/2 - 13 for head bolts"