How to I.D. the different /6's.

And here's a nice clean table:

Chrysler Slant Six Block Casting Numbers
Filed under Mopar Six Cylinder Casting Numbers

The slant six engine was introduced in 1960 in two versions – 101 hp, 170 cu. in. and a 145 hp, 225 cu. in. From this modest beginning, the slant six built its reputation for performance and reliability. At the end of the ’69 production year the 170 slant six was dropped and a new 198 cu. in. version was introduced to replace it. At the end of 1974 this version too was dropped and only the 225 survives.



http://www.hotrodreference.com/8/chrysler-slant-six-block-casting-numbers/