Make sure you don't have the two sides mixed up (there is a left and a right). I don't believe the weight of the engine will compress the safety mount rubber very much, mayb 1/8"? Someone will be along shortly.

 

They will fit. You just have to perservere. I had the same problem when I put mine in ... twice. The first time when I repleaced the 65 mounts and then last spring when I redid my whole front suspension.

If I remember correctly, if you put the long bolt through the wrong hole they won't line up but the correct hole was hidden by the mount so I didn't see it.

 

I only have 1 set of holes to choose, thru the brakets and the mounts.
Correct me if I am wrong but the 66 mounts have a right and left bracket but the mounts will fit either side. Right?

 

You are correct. The frame mounts are marked R and L

 

I can`t imagine any amount of compressing making much ao a difference ::
You sure you have the right ones?

 

My prefered "Made in India" Motor Mount tool;

http://www.coastaltool.com/hand_tools/channel_lock/images/460.gif

 

The saddle of the motor mount should fit over the frame bracket. You shouldn't have to bend or squish anything. Also check the alignment of the holes on the frame bracket itself. To fit in a '65 the outermost hole needs to be in the radius curvature of frame bracket. Note that on '67's the bracket is the same but the hole is not in the radius curvature and is drilled more towards the engine. The brackets should install easily and rest at a 45 degree angle to horizontal. Parts should look like these:

http://johnsmustang.com/Parts/details-4097.html
http://johnsmustang.com/Catalog/290/

 

The fit and quality of aftermarket mounts is variable. It sounds like you have a minor alignment problem. This has been my experience several times. An alignment punch and a large set of channel locks as shown by Art did the trick -

 

Thanks for all the help. I feel confident my craftsman channel locks and my trusty fid (from my coast guard days) will accomplish the task.

Now I can hopefully fix that exhaust leak - but I can't remove the header with it butt up against the shock tower. It is truly amazing how one job leads to so many others - but the toughest part is explaining the reasoning to swmbo . Luckily I have a very understanding one ::