Seat foam and springs.

[flyingskibiker]

I've heard of stuff like that.  Also, the back's pivit bolt/stud being torn out of the bottom frame.

[68Zproject]

From the looks of it, looks like that part is spot welded (2nd pic).

[KevinW]

Just saw this.  I recovered my standard interior drivers seat last year. I used foam from Ricks (which was from classic mustang I think).  The PUI covers went on OK, but the pleats do not match the originals.  Going to redo with Legendary when I have some $$. I had to use cotton batting to puff up the bolsters a bit for a better fit.  I also had the lean, but my frame was good.  comparing it to the pass side, what is happening is the metal arms on the back start to bow outward over time and that leans the back (back).  I pounded them straighter (comparing to the pass side as I went along).  Once the curve of the arms matched, the lean was fixed.  I also used jute carpet underlay for the layer ontop of the springs instead of the burlap (and burlap with springs).  It holds the top of the springs much better and is a stronger foundation to lay the foam onto.  the only issue is it is thicker to push the hog rings into. my .02

[adams69camaro]

So I know the purists will kill me but an outfit called TMI makes a "sport seat" modification that uses the original frames and gives you an actual comfortable seat.  I have not done it in my car yet but I plan on getting a new set of seat frames and turning them into the sport seats so I can retain my originals for show and also have the sport seats for travel.  None of the original 69 seat bottoms I have had over the years are very supportive when rebuilt to stock configuration.

 Also for anyone interested, there is a seat rail extender you can get to attach that will give you an extra 2 inches of leg room for either the driver or passenger or both.  They are an original part you could get installed at a dealer in 1969 and are available from Performance Years INC for $59.00 a set.  Well worth it if you are over 6 feet tall. (I am 6'5" and the extra leg room really makes a difference in my 69)