whats the difference

[xlisiv]

whats the difference between a 7.3 block and a 6.9? 7.3 is a straight block and the 6.9 as an adapter plate?
Thanks

 

[towcat]

the externals on the 6.9/7.3 are close enough that you can't tell them apart without checking out the headbolts. 6.9 uses a 7/16 12pt socket whereas the 7.3 uses the1/2 12pt socket.

 

[Freight_Train]

Head bolt size and the size of the Cylinder bores.There might be a few other smaller changes but I think that is about all there was block wise.