403 V8 and loaded up. This looks like it has the Limited option with the extra cushy interior. 1979 Buick Estate Wagon - cars & trucks - by owner - vehicle... (craigslist.org)
Well, I wasn't able to find anything on the '79 Buick models, but I did find something concerning the 1978 models. Check out what this brochure page states.... Read under 'Topping Off Your New Buick': I suspect in this case the moon roof may be an aftermarket installation.
I’ve also noted in a few other Buicks the use of a Cadillac steering wheel. Since Buick had it’s own steering wheels, I always wondered why
After market sun/moon roofs were relatively common. Photo is no close up, but the one on this Buick looks much better than the usual hack job. The curvature of the glass follows the roof very closely.
Price drop to $3000. 1979 Buick Estate Wagon - cars & trucks - by owner - vehicle... (craigslist.org)