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Discussion Starter · #1 ·
I picked up a new 5 speed Tremec TKX in January, and am just now getting around to installing it in my '68 BB. The new TKX is marketed as a more compact version of the TKO, that fits into more cars without modifying the trans tunnel. I'm wondering if anyone else has had the opportunity to fit this combo together, and what to expect?
 

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Discussion Starter · #3 ·
I will. But I was wondering if anyone else tried yet, as I am curious about trans tunnel clearance. I know that the regular Tremec trannies did have clearance issues in the gen 3, but that the new TKX is supposed to be a better fit in the old muscle cars.

I just received a supposedly new Lakewood stock type bellhousing from Summit, but it arrived scratched and nasty/dirty. Now waiting on an exchange. My car came with an odd truck bellhousing that I am switching out.

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I recently installed the TKX in my 72’ that originally came with a 350 small block and TH350. I did a Muncie 4 speed swap a few years back. It was close but it did fit within the tunnel confines. You obviously have to cut the tunnel for the shifter. Used my existing Z bar clutch linkage. Finding a cross member that actually works could be a challenge. The mount is about 2” further back than the Muncie or TH350. You need 26 spline clutch disc and a 31 spline yoke and I had to have my driveshaft shortened 2.5 inches also Bell housing has to be aligned to the crank better than .005 I did notice in my case the bottom of the TKX sits about .750” below the sub frame so gotta think twice about going over speed bumps. Overall love this transmission so far.
 

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Discussion Starter · #5 ·
Thanks for the info. I installed a Tremec in my '67 Chevelle several years ago, so I know the drill. The Nova already has a Muncie, so I hope the hole fits the TKX shifter. Bought an offset shifter setup to match the stock location, and a yoke to give to the driveshaft shop. From the literature, I don't expect major issues with the crossmember. Also bought a dial indicator to check runout. It's good to know that yours fit without cutting the tunnel.
 

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I can confirm that the TKX shifter location lined up perfectly with the hole I cut for my powerglide to Muncie conversion. I would be very surprised if you have a problem with yours lining up. My kit came in from American Powertrain and I couldn’t be happier. Well documented instructions that were easy to understand.

Right now I’m checking the GM 621 bell housing for concentricity and parallel like was mentioned above. Everything else is done so I should be able to bolt it in if I don’t need offset dowels. Apparently the modern transmissions are very intolerant of misalignment, .005 inches!
 

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Discussion Starter · #7 ·
I can confirm that the TKX shifter location lined up perfectly with the hole I cut for my powerglide to Muncie conversion. I would be very surprised if you have a problem with yours lining up. My kit came in from American Powertrain and I couldn’t be happier. Well documented instructions that were easy to understand.

Right now I’m checking the GM 621 bell housing for concentricity and parallel like was mentioned above. Everything else is done so I should be able to bolt it in if I don’t need offset dowels. Apparently the modern transmissions are very intolerant of misalignment, .005 inches!
So far, all good news from everyone. Yes, I heard about the critical tolerances. For that reason, I bought a Lakewood repro 621, because of the good reviews I saw. A bit more money, but I hope for a good reason! I plan on starting on my swap next week. The local driveshaft specialists anticipate a 2-3 day turnaround for a custom driveshaft. Happy Thanksgiving, ya'll !
 
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