About the 5521 and the "FO" aspect of this car. As a start, there were some large dealers in Alberta and BC, and some years ago I met a KFOCI member and his wife in Alberta who were (especially through his wife) connected with one of the biggest western Canada agencies of Kaiser-Frazer. I forget his name/small town, but he was still driving his 53? Manhattan nicknamed the 'Blue Goose" Not surprised really that it could be in the Reynolds in the first place--no salt on roads, lots to begin with.
It was common practice for Canadian (and in other countries too) operations of car firms to source some finishing details locally, either to reduce import duties, or just being 'politic'. Studebakers in Belgium, Israel, and Canada are rife with these touches, including models that didn't get sold at all in the USA (6 cylinder GT Hawks, W6 six cylinder "Presidents in all but name" sedans, Hardtop Hawks after 1956 that weren't Golden Hawks, etc) Kaiser did have an assembly plant for a short time in the Toronto area Leaside, around 1950 (for the long model year 1951 models ISTR)
FO would apply to cars destined for Canada, as well as overseas, I think, although the DR should cover that as well. It could be that it "was a foreign order", such as a Canadian service man stationed overseas that arranged delivery over there for repatriation when his tour was finished, for tax purposes.
That the code 5521 seems to be a correct sequence number but unknown for US production makes perfect sense to me. Perhaps this is a carry-on touch for Canadian destined models after the Leaside assembly plant closed. About that time, I think there were changes to some aspects of Canadian duties and such under certain conditions (52 model year and after??) but can't remember what what the specifics were, since I was only born in 53 <GGG>