I've waited many years for this............................................

Well ordered the 8” ATI from Mark today.

Gonna start pulling the trans tomorrow and have the whole thing refreshened and add a little line pressure etc.

Hopefully it won’t be down longer then a few weeks or so. Get it up and running for the end of the summer...and more importantly dialed in for the Winter air.

Mark thinks it will pick up a good bit with his converter...

I’d love to gain .1-.15 in the 60’ and .3 in the 1/4...

Definitely shift shaft seal is the leak culprit.... 4 pan gaskets and 2 pans later...

And the tear down begins.... Got everything on the bottom off...just need to do the top stuff tomorrow..should have the trans out pretty quick, then off to the trans builder on Tuesday…

Sweet!! Looking forward to the results

That's a good looking C3!

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Do you have straight axle in the Corvette there? I am sure you are aware those are not the best for 60 foots as far as strength even with half shaft upgrades - is the 8 inch going to compound this problem at track. Great weight transfer though. What does car weigh like 3,500 pounds with a full tank? I really like that hood where is that from? A friend of mine has a 1970 Corvette he put a 9 inch independent rear in and could use a hood like that.

The car is still IRS. Has all of Tom’s Differentials hardened stuff in it...12 bolt spiders/cross pin, shimmed clutch pack (no springs). Pretty much the only 10 bolt parts left is the ring/carrier... and the carrier has been stressed relieved/polished..

Hopefully it holds...but it has been in there for 10 years with probably 120 passes in the 1.5x 60’ range.

But yeah I agree, the 8” ATI will be the true test for the rear end. I’d love to see a 1.399999 60’.

The car weighs right at 3700lbs with me in it, on skinnies. About 3750lbs on stock wheels/tires. Car has iron heads, AC, 4 boxes of Dynamat, stereo system etc.. it’s a heavy pig.

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There we go...

Now the waiting game begins.

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Here is photo of the 9 inch on the 1970 Corvette. The half shaft I think are 1480 series. Stick car 540 Donovan.

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Damn that’s a crazy setup. I’ve never seen one of those. Obviously a custom built deal.

Now RideTech is making a 9” IRS conversion but it’s like $12k.


If my 10 bolt breaks, I’ll probably go ahead and have the full 12 bolt guts installed.. it’s about $7k just for the diff. The only reason I didn’t do it originally is that the tallest gear you can run is a 3.73 and I didn’t want that much gear. So I kept the 10 bolt ring/carrier so I could stay 3.36. I drive on the highway a lot.


I’m sure you’ve seen it, but 427Hotrod has a killer Dana 60 IRS out of an old Super Comp car or something. It’s bad ass.

Yes this guy built in a garage were at a rental house we shared back in 1995/1996. I remember watching him built and getting parts before the internet. As you can see a lot of work and engineering in there. I had a 540 Chevelle and he had a 540 Corvette.

Do you and your Vette a favor and disconnect the kick down if you haven’t already.
It will no longer be needed with the new tree master converter.
My lil 406 would boil regular radials at 45+ mph in 3rd with no kick down cable.
Your going to be very happy with it. I beat the crap out of mine for 7yrs and had zero issues.
It was spec’d for my lil sbc and 4.30’s and a 28” tire.
My son now has it and my 15yr old stock rebld th350 in his bu behind his 600hp sb and drives it all the time too! He only has 3.42’s in his car and nets 1.50 60’s leaving off idle.
I spoke to Charlie P down there. Good guy.

I'm sure by now you've already replaced the stock sprag assembly. Final weak link in my trans was the input shaft and forward drum. If you haven't upgraded it yet, consider the 300M input shaft and drum.

https://tsirace.com/shop?olsPage=pro...d-forward-drum. After that, it's really just about keeping temps down.

Finally got the trans and 8" ATI converter in. The trans was still working great but turned out to have a good bit of damage in it. Clutches were about done, sprag was cracked and the splines were about half worn off the pump stator shaft... I guess 168k miles on a pump will do that.

So its all back together and seems to be working ok, just waiting for some cool weather now to hit the track. I'm VERY curious to see what it picks up. The converter feels VERY loose at WOT... I guess we'll see.

As for the driveability, it IS driveable, but certainly not pleasant. I won't likely keep this converter in it after some track testing. No way I could take it on a long trip with this converter in it. Time will tell...

Tiny little sucker. Weighed 20.5 lbs.