Hi and welcome.
To the best of my knowledge neither Chance nor Fiesta Glass (who took over production in 1981) made a 45th anniversary plate. In fact, I'm fairly certain a 35th was never made, so I'm not sure where that one came from unless they produced a short run.
Fiesta Glass are almost certainly the makers as they started introducing these plates with ever more elaborate decoration, and it probably comes from its Jewel Glass range. This range commonly had 25th, 40th and 50th as the usual culprits, according to the scans I made of the promotional cards.
BUT, if you do find a 45th, I would be interested to learn of it!