# 1968 Tremec Conversion



## knucklehead12 (Nov 14, 2013)

I am looking I at converting my original 1968 GTO 4speed convertible to a Tremec 5 or 6 speed transmission. Looking for advice if anyone has done this already. Need to know what model Tremec to look for and where you purchased your conversion kit. Also, how you like the conversion. Thanks,
Lee


----------



## 68-GTO (Oct 20, 2013)

i have do a Tremec T56 Magnum conversion in my 68 Hardtop.
The tranns work great.
i have a hyd. mcleod twin disc clutch in.
you have to cut out the trans tunnel and weld in another one.
the new one is in the conversion kit.
i have bought all by hurst drivelines.
while i´m in Germany hurst dont send me a driveshaft, but when youre in US they the send the shaft with.


----------



## ALKYGTO (Mar 29, 2010)

I've got the Tremec TKO 5 speed in my car and love it. 

I bought my kit from Keisler but they are no longer. Other vendors sell this trans and there is also a newer version that supposedly needs no floor modifications but I have no experience with that unit.

The TKO did require some floor alterations but it's really not noticeable with carpet in the car. Very easy to fab and if you have a mig welder it's an after noon project. I would say if you had a four speed already and some skills you could easily do this in a weekend if all the parts were there and ready to go.

I went with the TKO because
1.) the ratios are very close to a close ratio Muncie
2). I don't need 2 overdrives
3). 100 lbs. lighter than a T56. 
4). Shifter is in the stock location
5). Was able to use stock trans cross member (fabbed my own later)


----------



## knucklehead12 (Nov 14, 2013)

With so many different models of the TKO, how do you know which one to look for to use in my old Goat? I assume you cannot use one of the Ford Mustang models that seem to be quite plentiful. The GM models are scarce. Also, any advantage to a mechanical vs hydraulic clutch? And if you go with a hydraulic clutch, is there any modifications needed, or does the conversion just bolt on.


----------



## Bensjammin66 (May 12, 2009)

I also have the TKO 600 in my '66 Le Mans. Glad to help you any way I can also. 

As far as which one to use I vote the TKO600 for the strength and ease of install. It has a .64 5th if you freeway cruise. The T56 has a .50 6th gear for comparison. They have a .82 5th gear model tko600 too but if you want awesome low rpm freeway cruising dont go that way. Not many differences from a 4 speed just fab the floor and address your drive shaft length. Also they take a 26 spline clutch not the 10 spline. Shifter obviously. Can reuse the cross member and bellhousing, linkage etc.. Not much else different. 

I run a 26.5" tall Nitto 555R on back with a 3.73 gear, in 5th i am approx 2100 rpm @ 70mph getting 15mpg from a KRE headed 468. Not bad! 

Side Note: If you are making some serious power be careful going into third. The shift rail or fork for third has a weak spot. The guys at Virginia Machine have told me stories of 550-600 lb ft motors breaking third gear by power shifting. I make roughly 500hp and have had no issues to date and i thrash it some days.

As far as going hydraulic I cannot comment because I have linkage. I fabbed up my own linkage rods with threaded rod and heim joints ( I can post a pic of them ) and it reduced the linkage drag drastically. Not quite as smooth as hydraulic but its still damn smooth and MUCH cheaper for sure.


----------



## bondobill (Oct 24, 2011)

My son and I are in the middle of swapping out his factory 4 speed to a TKO600 in his 68 GTO.
As Bensjammin stated the TKO has a 26 spline shaft. We found that out after we received the tranny. Not a big deal altho the clutch we had in the car only had 600 miles so we had to replace the clutch again. That's a whole nother story .......
We have the new so called "streamlined" version of the TKO.
You still have to modify the tunnel. WE had to raise the top of the tunnel forward of the factory shifter hole about the width and length of his console.

We purchased the Perfect Fit kit from Silver Sport Transmissions.
I got to say they have been great to work with. I think we had the transmission within a week from the day we ordered it.

Bill


----------

