New carpet is available as are new covers for the 76-77 style buckets and the coupe rear seat.
Hardest thing to find is the 78-79 grilles especially the 78-79 Volare grill.
Urethane isolator bushings for the K and rear suspension are pretty cheap.
The bent T-bars leave a lot of room for header choices.
Every one has disc brake front and 10x2-1/2" rear drums with the 5 on 4.5" bolt pattern so no upgrading required.
Most were column auto's.
Manual brakes and manual steering are very unusual. Only ever had 1 with manual brakes (out of several dozen) and none with manual steering.
I find them easier to work on than a B body and even an A. I dont do E so I cant comment on that one
Over all a very nice driving line of cars.
Lots of good used parts for them around if you know where to look