Hy PaddyPhelan, welcome, please remember to tell us the model designation of your truck in every one of your posts, 1300, 1400 etc.. Canadian casting numbers are different than their American cousins in some cases. If your truck is a one ton or less it probably has a 216 Babbitt bearinged engine in it. Before trying to free the engine up, remove the valve cover and check for stuck valves and bent pushrods, hope that helps.
