Swapping seats in an X1/9?

Will seats from a post 1980 fit into a 1977? Are they a direct fit or would they require modification?

Thanks.

77.....

has half the rails welded to the floor pan, and what a pain to remove. That being said, I don't know if the later rails will slide apart, allowing you to use the upper part on the 80's seats, with the welded rails in the 77....
If you have to remove your rails, I can say, it's not fun.

74-82 use the welded rails

You should be able to swap in seats from any 1974-1982 X. Maybe even 83 is welded. Bertone switched to the bolted in tracks, so those would require mods to the rails welded to the floor of your X.

I've done just the opposite twice...

No problem... just remember to clean the rails, lube them with grease, spread the female rail section apart on the seat (backside) so that it acts like a guide to get the seat started... Push the seats against the console when aligning them on the tracks... toss those *&#$%*#* springs and they should slide right on.