I've seen Nova's with straight six's, but the Buick's got the 231 unless it was changed out by the owner. The Factory Service manual (for all the Buick's that year) does not show any information on a straight six, I'd be very very surprised if GM shipped some out that way. That and there is no VIN engine code for a Straight Six.
Well, my front bumper, clutch pedals, rods, & z-bar, tail lights, bumper fillers, and arm rests came off of a '77 or '78 that was straight six standard shift. Looking back, I wish I would have picked up all the non-air stuff. If it was not born that way...whoever did it put everything in it like it was OEM. The guy told me he had a 'gauge' dash for it somewhere. Ended up calling me a few months later with a tach/gauge dash too (NOS) with the RTS decal on it (Radial Tuned Suspension). Oh, and a rear sway bar and the lower spring perches that they attach to. He wasn;t going to part with any of it, then he seen my car with the 455/M21 all sleepered up with dog dish hub caps and bench seat and thought it was cool and let go of the stuff. I later traded him a '79 Olds Omega SX for the rest of his Skylark. It was a bucket/console hatch car that also had the rear sway bar. I haven't seen that many on X-body cars.
Nova's and Omega's got the round pod Gauge cluster with the tach, temp and voltage. Pontiac had an entirely different dash cluster set up. The Buick as far as I know, including the S/R models, never were offered with the Rallye Pack of gauges. I currently have one out of an Olds Omega in my Skylark. I know clutch linkage would work with the V6, I6, Small Block Chevy, Small Block Buick and Big Block Buick. Maybe with the Olds and Pontiac mills as well but I'm not sure. Basically it's easy to swap an I6 in a car. But the fact there isn't a VIN code for it tells me legally the factory never put one in the Buick.
