For the Cobra, do you know offhand what the spline count is on the end of the halfshaft that mates with the inboard CV? Not the spline that goes into the diff, the one that goes into the inside component of the CV a.k.a the tripod. It is not something you can check unless the boot is off of the CV.

Sorry, I was away for a day. I have the T-bird and the FFR halfhafts in my car. Not sure if the NB subframe is different or not but it fit easily. I Sawsalled the old diff mounts off. At least a couple of fingers between the diff and the tank. I can't access my photobucket at work but there are assembled pics there if you follow the link from my build thread.

Thanks Stein, no worries. The two finger measurement is all I need to know, and somehow that method of measurement fits the theme of this thread.

I talked with the Driveshaft Shop this morning and they are looking into a driveshaft option based on the measurements I provided. I'll let you guys know what I find out.

I got my driveshaft from Southwest Speed. All new, $169 complete with front yoke (for my T5) and u-joints. IIRC $181 shipped. They sell them from stock in 1/2" increments. Shipped the next day. Might be an option to explore.

Sorry, should have said halfshafts. Driveshaft is fine AFAIK.

More information on Driveshaft Shop halfshaft options here. Linking instead of repeating. Bandit you probably saw this already.
http://forum.miata.net/vb/showthread...=366129&page=3

Update: Currently modifying a subframe I am going to swap in. I am cutting the excess fins off of the Explorer housing and using a template I made of the floor/gas-tank to check for clearance. It looks like I will be able to raise the diff about 2.5"-3" above where it was before which should give me the halfshaft angle reduction that I need.

Hell if I get this done quickly enough I will be able to track test it next weekend.

Updates
Fins removed from top of differential
http://lh6.ggpht.com/_jh2HiMm4nKQ/TH...0/P8210143.JPG

Modified subframe
http://lh6.ggpht.com/_jh2HiMm4nKQ/TH...0/P8210144.JPG
http://lh4.ggpht.com/_jh2HiMm4nKQ/TH...0/P8210145.JPG

Welds are not pretty but they are very beefy. Note the reinforcement plates. Also note the front diff mount, and the through hole mounts added for the diff.

New mounting location is about 2" higher in the car so it should take care of the problem. All I have to do is wait for the paint to dry, remove the old subframe, swap over the control arms, install this subframe, install the diff, and reinstall the rebuilt halfshafts.

So glad you have a decent rear end mount and not an obnoxious one...... Looks good man!

All that in 100 degree temps...what a bad ass. That's what I call motivation. I, on the other hand, spent the day installing part of a drip irrigation system at the house. I sure would like at least a little rain sometime before the year is up. I am finally picking up the Miata tomorrow so some work may actually progress on it for a change.

My excursions outside today were as brief as possible. It is freaking hot people. August in South Texas FTL. 100F+ temps with 107F+ heat factor. Hell it is well after 10 pm here now and the heat index is 97F. The only nice thing about it, and I do mean ONLY, is that black spray paint sitting in the hot sun dries very, very quickly. It is like I baked it on.

If I were installing drip irrigation today I would have had it irrigating me during the installation process.

Just got back in from dropping the subframe. Though I expected it would not be too bad, it was even easier than I thought. Going from sitting inside getting motivated to do it, to the subframe out of the car and sitting behind it in the driveway, took less than 30 minutes, single-handed. Pneumatic tools FTW.

Tomorrow I use rlogan's pressure washer to remove exploded cv grease and 16 years of road grime from the old subframe. Then the suspension gets swapped over to the new subframe. Then it all goes in the car.

It's in. No ass pounding required though the clearance between the top of the diff and the gas tank is close. I added a heavy foam spacer in between the two just to be safe. It could not be any higher in the car than where I have it now without removing the gas tank. The pinion angle also looks pretty good as well.

http://lh4.ggpht.com/_jh2HiMm4nKQ/TH...4/P8220150.JPG

http://lh5.ggpht.com/_jh2HiMm4nKQ/TH...2/P8220154.JPG

http://lh5.ggpht.com/_jh2HiMm4nKQ/TH...0/P8220158.JPG

UPDATE:
The suspension and halfshafts are back in the car and everything is looking good. The halfshaft angle is much, much better. At full suspension travel they are actually sloping downward towards the outboard end; at the midpoint of the suspension travel they should be very close to level.

I think I have this one solved though I will know for sure when I get it to the track. Hell if I ever do another rear differential conversion I'll just modify the stock subframe and save money on the conversion kit. This one was not too bad, but with a Thunderbird style housing it would be even easier. It makes me want to drop an 8.8 Ford truetrac into the turbo car as a preemptive measure :)

HOLY WOW!!!!!!!!!!! What is the measure difference? Looks like 3+ inches, and now it fits as well as the TII mutt I have in the back of my shitbox!

Looking good, thanks for the help yesterday...btw, I went to swap the input shaft oil seal and I need a gasket for that cover. Oh well, I need a few things so I'll order them all at once.

It is at least 2" higher, maybe 2.5". Before the bottom of the diff was lower than the bottom of the subframe. Now it is the same or even a little higher. It absolutely cannot go any higher with the stock tank :) I did not get to put it on the ground over the weekend but everything is bolted in. I just need to find some pinion nuts and then torque it all down.

DOH! I do not remember a gasket there. Oh well.