Rashi in Parshas Bechukosai פרק כו פסוק מב says there are 5 places that Yaakov is spelled with a vav like this יעקוב & Eliyahu is spelled without a vav like this אליה.
The first full spelling of Yaakov that I know of is the above Pasuk. I know of one place where Eliyahu is spelled missing the vav. That is in מלאכי פרק ג פסוק כג. Where are the other 4 places in Tanach where Yaakov & Eliyahu are spelled differently than usual?