Early vs late 71 bucket seat ?

Couple ?'s on bucket seats for 71 demon, i have a late 4/02/71 demon 340 bucket seat car, and i'm looking for a set mine were missing when i got the car :angry7:
1 * Should the seat have the long rectangle button or smaller one?
2 * should the track have the (L)? brackets, my mounting holes are
12.5" front to back & 12.5" side to side, so its square.
3 * i see seats that look correct but don't have the (L) bracket, were these
removable from the track itself ? are these repoped?
4 * NE1 have a few good pics of the bottom and sides of the late seats?
5 * NE1 have a good set for sale or trade? sorry had to ask:cheers:
Author: admin