I don't have easy access to the attic to remove the existing housing, but the dimensions are identical and the wiring is already done (two switches - one for fan, one for light).
769 fan specs are here: http://www.nutone.com/products/product/767f914f-2ee6-4f40-965c-7d859b8583ce
I didn't have luck finding 669 fan specs online but the housing says: "120V 60Hz 1.6 Amps MAX"
Can I go ahead with the existing housing / power outlets or would it be better to wade through the insulation in the attic and re-wire / use the newer housing?