I want to install an OD trans on my 68,but can't get a clear picture of the right combo. What I have: 383 crate roller, approx 450 HP, TH400, Ford 9" posi with 411's. I have a 3:73 gearset in the box. What I want: good light to light action with decent Hwy. MPG. I have heard that a 200 can be performance built to handle 400 to 500 HP. Any truth to that? I have heard that a 700 is the way to go but 1st gear is too low for 411?
What about with 373's. Which is the easier swap? Does either one need a different crossmember? Driveline mods? Converter choice? And what about the lockup? I'm still unclear about how this works. Lots of questions, but I need help in deciding which setup will work best.

I have almost the exact set-up that you are talking about. (My ZZ430 is currently being stroked to 383) I am using a Bowtie Overdrives http://www.2004r.com/trans/level3.shtml level 3 T2004R, and 3.73's. IMO, the T200 and 3.73 is an excellent combo. I did a fair amount of research before deciding on a 700 or a 200. I chose the 200 for the following:

- A better rep for durability if built properly

- Better gear spacing than the 700 (but not as good as a t350)

- Easier to swap in place of a T-350 or PG than the 700 (No driveline cutting - but not a huge issue)

For a crossmember, I used a T400 unit. You have to cut off the mount pad and re-weld it in a centered location.

I think that the lock-up is a great feature. I don't know of any good reasons to do away with it. The unlock wiring is pretty simple.

The 700 has a 3.06 first gear, the 200 has a 2.76 first gear. I think the 3.06 and 4.10s would be pretty steep.

I'm not knocking the 700 trans here - it just seemed the 200 was a better fit for me.

PS If money was no object (sadly, it is!) I would have these guys build me a 200 http://www.ptsnctb.com/index.asp

Thanks for the info and the link to the website BPOS, lot's of info there. The level 3 is not as much $$ as I expected. Can you elaborate more on the lockup feature and why it's needed? Is it because the car lacks the computer control?

These transmissions all came from the factory with the lock-up feature. What it does is "lock" the converter when in overdrive, doing away with the normal fluid coupling slippage. It is done to improve fuel economy as well as to make the trans run cooler. My transmission is wired internally to automatically lock up very soon after shifting into fourth (OD). The un-lock on mine is activated by wiring that is hooked up to brake light switch. This assures that the engine won't stall if you hit the brakes while in lock-up. This whole system is done without use of a computer.

I'm learning a lot today,.. so the lock-up is purchased seperately or does it come w/the trans. or is it something you had to do? ( I haven't had time to check out the website at length).

The internal lock-up wiring is included with the trans unless you specifically ask for a
NON locking trans. (The lock up system is disabled) Actually, the true part that locks up is in the torque converter. The torque converter is not included with the trans - you need to buy it separately. If you get a lock -up trans, then get a lock-up converter. If you get a non lock up trans, then get a non lock-up converter.

I recommend lock-up. It's very cool. :cool:

Thanks for all the good info BPOS. Now all I have to do is convince the wife we need a new drivetrain for the "toy". Can you help me with that too? :D

I second the 2004R/3.73 combo!! It works great running around 2100 RPMs or so at 65 and with my 383 I got 21 mpg once (usually 16-19).

Let's see, to convert if I remember everything:

- TV cable
- TH400 cross member modified as mentioned
- linkage conversion kit (from Rick's or Classics)
- 2004R requires no driveshaft mod while 700R4 does

That's all I can remember. The converter for the 2004R is a lockup converter. All that you have to do is wire it so that when it's in OD it locks up. I didn't wire anything to the brake switch and I haven't been able to stall it by mashing the brakes while in OD and I tried a bunch of times.

Shift timing is determined by the valve body, governor weight and springs. To get yours right (mine shifted at about 3800 stock) you may have to mess with them...or just buy one from a pro!! I took a 2004R out of a caddy and with the help of a friend rebuilt it and messed with it and messed with it until it worked the way I wanted it to.


I would like to qualify my tranny knowledge by saying that I have only messed with ONE 2004R my whole life, so I am NOT a tranny expert by any means!! Just sharing what little I do know (or at least think I know). :D

I have found that it's usually easier to get forgiven than it is to get permission. ;)

Interesting note on the un-lock wiring, Paul. I always assumed un-lock wiring was necessary - know I know differently! Also, when the trans shifts out of OD into a lower gear, it unlocks automatically.

383 - In your case, since you have a T400 in there now, you'll need a LONGER driveshaft and a different slip yoke.

I have found that it's usually easier to get forgiven than it is to get permission. LOL!! That's for sure!!

I think I see a pattern here. Thanks BPOS and paulm. graemlins/beers.gif

Is there a link somewhere to show me how to wire the lock up, to the brake light switch? Do I need a new brake light switch with a extra terminal? thanks for any replys.

I'll third the 200/3.73's

Originally posted by loaded67:
Is there a link somewhere to show me how to wire the lock up, to the brake light switch? Do I need a new brake light switch with a extra terminal? thanks for any replys. http://2004r.com/tech/tcc/index.shtml

Scroll down to the "Brake Light Switch" section. This is how I did it. The switch is a GM cruise control switch.

Also, see the above post. PaulM uses no unlock wiring and hasn't had a problem.

BTO's towing option leaves a little to be desired. It locks the converter when you flip the switch and it will also lock when you release the brake. I use a latching relay to lock and unlock the converter. It won't lock when the brakes are released, only when I push the lock button. When I hit the brakes, the converter unlocks and doesn't lock again until I lock it.

visit www.ckperformance.com.click (http://www.ckperformance.com.click) gm 2004r 0r 700r4 for a thorough explanation of what is needed at what power level.we also have a book coming out in february on the 2004r .if anyone is interested contact us at www.ckperformance.com (http://www.ckperformance.com)

I'm running the 700R4 with the 3.73, but less than 350 HP. I think because there is such a demand they are getting a lot better at beefing up the 700's. I had them build mine to handle up to 500 HP as I will get there someday. Either way, it's going to give you an ear to ear grin. I put it under the money well spent category!