Was there any type of body filler used in 1964-65? The reason I ask, I have been sanding my car and i seems that there is some type of body filler used to join the rear quarter panels to the quarter-panel end caps. I know they used seam sealer at the joint of the two, but mine just don't line up. By about 1/8 to 1/4 inch. The end caps stick out off the side of the car.
I've looked inside the trunk behind the rear wheels and there is no dents or body damage of any kind that I could find. In fact, the original undercoat is still there. So it makes me wonder if this was done at the factory to make it seamless. But I didn't think there was any kind of body fillers used back then, just lead. (???)
If this is not original, I am not sure how to pull the quarter panels back out. The tops of the end caps look fine and line up correctly. It's just as you get near the bottom outside, it gradually sticks out. Like the quarter panels are in too close at the bottoms.
If the body filler does not belong, any suggestions on how to pull the rear, bottom of the quarter panels out a little bit. Bolts too loosen or am I looking at some metal work?
Thanks all!

 

The short answer is no they didn't use any filler on the quarter extensions. Are your quarter panel original? The 65 and 66 quarter extensions are different by the way. The 65 had a thin side wall and the 66 had a thicker wall with a groove to accept a seal. I have found that it is much better to modify the extension and not the quarter panel. Look and see what is keep the extension from going in to match the quarter. Some times it will be the mounting studs in which case you can oblong the moung hole slightly. Sometimes it will be the extension hitting near the tailight in which case you can slightly grind the extension to get it to move in. Hard to say without seeing it. The thin walled 65 extensions can be tapped on to recurve it to match the quarter but that is difficult on the 66 because they are much thicker.

 

only "filler" i know about was lead used to transition between the sail panel and the actual quarter panel.

 

I actually have seen plastic body filler under factory paint. If a panel was slightly damaged when the car was going down the line I think they did use plastic filler in some rare cases but not to fit the quarter extensions.

 

all cars use filler from the factory be it lead or plastic etc

 

I think it was the bumper that caused the problem. The body is all original including the quarter panels, trunk floor and tail-light filler panel. The reason I mention all these parts. I knew the bumper was not for this car, I had a mechanic/Mustang parts shop look at it and they decided it was from a 1967. Not only is it abut an inch longer, but the mounting holes are different. The person who did this used the original brackets from my 64.5 and only 1 bolt in the bumper on each end itself to hold it on. (the 2 holes on the bracket do not match the holes on the 67 bumper)
I had noticed a slight bow in the tail-light filler panel and had planned to straighten it out while doing this paint job. It bows in slightly. Anyhow, when I took of the bumper, the two screws holding it to the mounting bracket where not even tightened down all the way. They couldn't be since the holes did not line up correctly. It was tension against the body parts that was holding the bumper on. When they tightened the bolts down to force the brackets into their correct position, the bumper pressed against the rear body parts. I believe, it may have bowed the tail-light filler panel and the floor of the trunk as well. Maybe even bringing the quarter panels closer to the center.
I really think this is what may have happened since the brackets were bent and you can tell they used the bolts to tighten it down to the car, forcing them into their original holes. Probably bringing both side of the car towards the center by less than an inch. The mounts were bent and the bolts stripped. It looks like they used the bolts to force the bumper brackets into position after bolting on the bumper. And there was a noticeable release of stress on the mounting bolts after I managed to get them loosened half way!
I had noticed the bow on the tail-light panel since it pulled away/inward from the fuel filler pipe when I got it. I think the rest of the rear of the car may have pulled inward when I replaced the gas tank since right after that I noticed that the seam sealer around the bumper mounting brackets inside the trunk (the brackets on the floor that the tail-light panel, bumper brackets and rear frame rails mount to), had cracked and slightly lifted off the floor. Just slightly, so that a few sheets of paper can fit under it on both sides. I think that removing the gas tank allowed the pressure from the too-tight bumper to pull the floor closer together.
Is this possible? Using the smaller mounting holes of the bumper placing tension that caused these pieces to bow slightly? How could I correct it? Needless to say I have removed that bumper and it won't go back on. Any suggestions? Is there a way to confirm if this is the problem? Measurements between rear frame rails?

 

Here are some pictures. This first and second one show the slight bow that I mentioned in the rear panels. As well as the mounting brackets for the bumper in reference to the bow.


This next one shows the cracked and lifted seam sealer on the inside bumper mounting bracket. Like the brackets have moved or shifted out of position.

This last one shows the quarter panel end cap. The body filler removed. The gap gets wider as you go towards the bottom (where the bumper was mounted.) It looks like the quarter panels were moved in toward the bottom.


When I thought it was the tail-light panel that was the only bowed part, I had a plan to fix it. I was going to remove the filler pipe. Insert a flat 2x4 board the length of the panel with an eye-bolt hooked on. Put it inside the trunk, with the eye-bolt through the filler panel. Connect a ratchet cable to the eye-bolt and the other end to a solid object. Crank the ratchet a couple times, pulling the panel out till it is straight. Should I still try this? Would mounting the correct bumper and tightening it down help straighten it out? (haven't got it yet, so don't know.)
Any advice would be appreciated!

 

Mine have the groove for the seam sealer, so they are 66? The bolt holes keep me from being able to move them in at the bottom. I'll keep this in mind while working on it, but I think that is only part of the problem.
I posted some pics above, if they help.

 

The taillight panel should be curved. It is not a straight piece from the factory. If you look at the back of your deck lid you will notice that it to is curved. Everything I can see from the pictures looks normal except the amount of bondo in the right quarter. You might want to start by grinding all that out and that should give you a clue as to why the quarter cap does not fit.

 

The groove is actually for a rubber seal that should go in there not seam sealer. I would NOT try to crank out the tail light panel. It looks absolutely normal to me. I would grind the bondo out of the quarter and see what is going on there. The difference in the quarter cap might be a mid year 65 change but if you have a known early 65 or 64.5 those caps would not be original to the car.