Canadian Rations 70s-80s era

[fallout]

Hello all, I have a few questions on Canadian rations. I know that the Individual Ration Pack(IRP) was the type used from the 60s into the 80s, this is what I have seen:

1975 dated in a box:
http://www.armycadethistory.com/Odds%20 ... 0Packs.htm

1979 dated in plastic bag:
http://www.network54.com/Forum/28173/th ... /1979+IRPs

At some point between 1975 and 1979 they changed packaging, do you know what year? Then I also know that the Individual Meal Pack(IMP) was introduced in the 80s at some point but I have no idea when, what year was it introduced and replaced the IRP?

Side note here is a cool video of one from 1991:



Thanks for any help and info, also I am after 80s era Canadian rations if you are selling any or know where I could get some.