will do, my car has loads of rust, originally a northern car. the mounting bolt that is there is so bad you cant see the "10" on it. I hope it doesn't break during replacement.

http://www.boltdepot.com/Fastener-In...Bolt-Sizes.pdf

I'm thinking the bolt is 10mm x 1.5, 1.25, or 1.0..?

I would take out the rusted bolt and see what size but i'm scared the same thing might happen to me and have to drill it out, still not knowing what size it was lol.

Dont Take it out unless you have to. Do your homework on finding out what size of bolt it is and save yoursefl the stress. The reason the bolt is missing in the first place is that is probably broke off inside when someone tried to remove it and that is why it isnt even there to begin with.
If you get the right sized bolt, Make sure you use an impact wrench to tr and tighten it. I think the slowness of me having to turn a wrench made my bolt seize faster.

Well a freind of mine had the bolt I needed from his Cressida build, which is the good news ( I belive it's a m14 x 35mm @ 1.25tp)

we both jacked up my car to put the bolt in yesterday and ran into quite a problem. the bolt holes where the diff mounts to the suframe are not aligned. spent an hour trying to get some play to somehow get it in but there was no luck. i'm guessing the subframe is tweaked seince there was only one mounting bolt..? =( the bolt goes in about halfway then taps the subframe, if you put your finger in the hole it feels like the hole is shifted like 1/4 inch to the side, if i use my pinky i can almost feel the cage nut inside the xmember but theres no way to get the holes to line up for the bolt to go in.

does this mean I've gotta get another subframe?!?! any ideas/options?

Check the top of the Subframe cage that goes over the Rear end for cracks. It should not be missaligned and i have never herd about any differential swaps causeing the issue of not ligning up.
To fix your Problem you can take a hole saw and drill into the subframe where the bolt and cage are located.(this is what i did on both sides).
It wont take you too long to do but you will need to weld the hole you cut out back in (I used a washer i bought at ace hardware) after you put in your new nut . I removed the cage inside and made my own design.
basically a piece of flat 1 inch steel with a Bolt welded on to one end so it had a lever or pivit point to press agains if i tightened or loosened them.
it sounds like something else is wrong. Check the Subframe next to the tank there are 4 mounting bolts you could have broken one of them and it twisted the Subframe.

Well this weekend I had some spare time and jacked up the car again for round 3.

http://www.toyota-supra.info/forums/...3&d=1266849127

the car won with a huge crack in the subframe!
I dont have a pic yet but It's about the same size if not a bigger gap and place as yours pictured above where the shaft meets the diff. =(

Is it possible to repair? I belive this is why my diff mounting bolt holes dont allign, and creates the clunking noise when not under load.

I'm planning on dropping the subframe and welding the crack hopfully everything will align if it's solid again? or should I hold out for another subframe?

Tripple C, what are you going to do about yours?

I welded it back together. I Took out the diff and swapped it for a welded this weekend and finished the welding on the botom side of the subframe Rail.
I started by welding the actuall frame back together then created some 3/4 inch flat pieces of steel and welded them on to the outside of the frame for more support. I also Drilled holes in the Metal piece so i could fill in a rosette weld and make it stronger. Not just an edge or rosette weld I put on some extra leyers on for mental security.
The frame is holding great and trust me i have been beating it to death. In fact it currently isnt running but thats not because of the subframe. i have ignition or Mainly fuel delivery problems

I'm going to wait out on another subframe in better shape and reinforce it, I didn't realize how much crap that area of the subframe is... apparently it is a common problem for 2 key areas on the rear subframe 1.) right where the front diff mounting bolts and subframe meet 2.) above the diff where it connects to the driveshaft. everyone should go under the rear of their car if not already done so and check these areas of your subframe. I suspect that age and the more torque the diff puts more stress that causes these cracks.

I found tons of info and pictures in detail about this particular problem
http://www.supraforums.com.au/forum/...p?t-43162.html

good plan on getting the new subframe. I will be doing the same time but in the mean time i am using what i have until i find one in my area.
If you had time and wanted a cage you should just try and build your sumframe into the cage. I know thats a big budget move but i dont know what kind of mechanic you are.
Weld it back together till you find yourself a new one, it takes hardly any time at all when you really think about it.

I'm not 100% sure if I want to repair my orig subframe or wait out of another one. My main concern is that maybe my subframe is twisted a bit and the front mounting bolt holes dont line up. =/ my crack is located right above the diff. seems like it's about to snap in half...

to weld or not to weld?

Welding - not so much money (some would say free)
New Subframe - More money then welding ($150 -1500)