First off, post the make of the car, delta 99, S coupe, etc., and maybe some photos of the engine and car exterior/interior, this would make things SO
much easier.
Technically, a vehicle over 25 years of age is considered "antique", yet most gearheads give it till 50 for it be be a true antique in their
minds.
I have a 71 rocket 350 S coupe, all original (currently being restored), and it runs excellent, just as it did with 10 miles on it. It's over 30, and
I consider it a muscle car, not an antique, but for the record books, let DMV sort it out.
It's all just paperwork anyway.
The most obvious thing that comes to mind in '77 is that Oldsmobile reached the 1 mil. mark of # of vehicles made in one production year.
Also in '77, Olds had to deal with the "chevymobile", in which they (unknown to the public or dealers) switched the olds rocket with the LM1 350
from Chevy. While this was still a GM product, and virtually the same, save some minor bore/stroke ratios, it no different, but with a rocket sticker
on the air cleaner. The public didn't really like being decieved, so Olds offered for thier customers to come back and swap it with a true
oldsmobile-motored car. This was not really rare, and was rather common. It created alot of stink with the buying market, but it didn't classify the
'77 as rare.
As far as the diesel, I don't believe that was an option until 78, to which buick also offered a 231 v-6 as option to the 350 as well. If your model
is a late '77 production model, it could be billed as a 78, but that can only be designated by the vin tag. This diesel was only put into the 88 and
98 versions starting in "production year" '78. The diesel came with a special rotary-injection pump to replace the car and distributor that worked
in sub-zero temps.
One special note though, in '77, after the gas cruch, olds was concerned about weight vs. gas consumption, so they opted for use of some aluminum
parts, such as a hood. Other parts may have been used fashioned out of aluminum, but I am unsure on what. They did offer a 4-4-2 option in '77,
although it was more appearance than anything, to which the front of the car was sloped.
I can't think of anything off the top of my head, but if you need more info, try looking up the vin classification and researching the head stampings
HERE
Other sites you could try are:
A good olds forum, dedicated to all things Oldsmobile
Olds performance site/forum
My favorite automotive site--any vehicle question on the planet you want answered.
I hope this helps at least a little, but I am interested in seeing what you have there, care to post some pics?
Good luck