Here is the information you need:
Type I
Term used to describe the very earliest of production Contender barrels (early 1967 to late 1967). These barrel are easily spotted by their "one line" company address and caliber designations. All Type I barrels are octagonal, have flat bottomed lugs, allen screw bolt retention and short style rear sights. To date, only six calibers are known to exist in this barrel type. They are 22LR, 22WRM, 22 Jet, 22 Hornet, 38 Special, and 357 Magnum. Type I barrels are known to exist in both 10 and 8 3/4 inch barrel lengths.
Type II
Designation given to the second style of octagonal Contender barrels (late 1967 to 1972). These barrels may be easily recognized by their two line address and caliber designations. Of further importance is the punctuation used between the "N" and the "H" used to abbreviate the words New Hampshire; both are followed by a period. (example - Rochester, N. H.). Type II barrels are also recognized by their flat bottomed lugs, allen screw bolt retention and short rear sights. Type II barrels exist in three lengths, 10 inch, 8 3/4 inch and 6 inch. These may also be found as "scope model" variations (w/o front sights). The largest selection of calibers exist within the Type II classification including all of the original 17 caliber offerings.
There are actually five types. Types I thru V. Information on other types can be found at:
http://specialtypistols.infopop.cc/eve/forums/a/tpc/f/387102585/m/1041006425Mike
