They are different, the 71-72's are more like Mustang seats. If you strip a 73-74 bucket, you'll find that the foam for the back section is molded around the seat frame, and not removable, like the earlier style (71-72, which you can use Mustang seat foam for replacement)
It appears they had some seat covers at one time, unless mavericks had velvet seat covers. I emailed Fred regarding some cover, would i be able to put on the 71-72 style cover on it without it looking like crap? Are the seat backs different? Mine has the lever on the side with the lock in the middle
I dont know about the back but my 72 seats dont have the lever on the side...I wish they did it would make it easier to lift them forwards
The foam on a 73-74 bucket seat back is quite a bit more substantial than the 71-72 style, I doubt the 71 style covers would fit over it. I stripped a 74 seat, just to see if I could convert to the 71 style, but the springs are different, it the back and the bottom. I had a line on some 72 Mustang buckets, but the deal fell thorough, I was going to take some pictures to compare them.