I had the same problem. It's not the casting number, but the engine serial number beside the distributor. Lucky for me the previous owner emailed me a letter stating he had replaced the cracked block which had the vin number.
I too got it across the border, the US agent came out and looked at it. When I came to the canadian side I gave the the vin off the door post which I assumed everyone would use. They too did not question the difference from the title.
I fought tooth and nail with ICBC and they finally gave in and registered the truck using the vin on the door post.
I was at the point of making a new metal plate to glue to the block, over the number, with the number they wanted to see. Never got that far thank goodness.
It was my agent phoning in to ICBC asking what I could do and pleading for an answer.
Good luck.
John
