The $1,000 is the strange one. It was issued several years after the rest of the 1937 series, took on the rose tint of the 1935 $20, kept Wilfrid Laurier and the security allegory from the 1935 issue, and exists in exactly one signature combination: Osborne-Towers, the pairing that ended in 1938. The printage stopped at 15,000 notes, the smallest figure in the entire series, on a denomination that moved between banks rather than between people.
That makes it the 1937 key by an enormous margin and one of the serious rarities of Canadian paper money generally. Certified examples trade in five figures in any collectible state, and the market for it is a market of provenances - most survivors are known notes with auction histories.
A thousand-dollar note that outlived its own signature pair. At this level the usual advice compresses to one word: certified, and ideally with a paper trail. A fresh discovery with no history deserves the scrutiny any six-figure claim earns.
Mintage figures: United States Mint (Annual Report of the Director of the Mint), Royal Canadian Mint records, and — for the 1935 banknote issue — Bank of Canada printage records as published in the Charlton Standard Catalogue of Canadian Government Paper Money, cross-checked across independent published references. Specifications: United States Mint coin specifications.