weird engine manufacture code

[70CitrusZ]

Update..
Now GM Canada says veh is too old to supply that information. (they don't want to look any more) Oh well, I just have to be content with the number being documented on the GM Canada build sheet docs I guess.

I have inquired with people who have GM parts books, and I gather that shows nothing.

Would have been nice to know why the odd number, but I guess it makes my car unique compared to all the other L36 cars in the world, so maybe thats a good thing.... a 1 of none engine in an already fairly rare car is a cool thing to have I guess.....
Thanks to all those who tried to help with this mystery!!
Mark.