Just had bob kelso build a 10 bolt posi for me. I am also rebuilding a 2004r to replace the 300 turbohydramatic. I want to hear what needs to happen as far as the cross member, driveshaft length, and trans mount? Its a 1968 cutlass supreme

 

On my 72 cutlass convertible, just moved the cross member back and picked up the bolt holes for the th400 position. The driveshaft for the TH-350 fits just fine. no length changes required. I used Energy Suspension transmission mount. everything just bolted right up.

 

Must admit that i am not familiar enough with 2 speed trannies to know. But is there a difference between to 2 speed and the TH-350. I know i will be having issues just trying to figure out the rear u-joint. What is the spines the same between the jetway and 350? Yeah i know...alot of questions....sorry.

 

I have a 68 cutlass supreme. Changing the rear axle to a 72 chevelle posi. Changing the transmission from a TH-300 (jetway?) 2 speed to a 1986 chevy monte carlo ss 2004r overdrive. ADVICE NEEDED..
Yoke splines?
Driveshaft length?
Trans mount same?
Crossmember moved back?
Anything else?

 

Yes, splines are the same.

 

The short tail versions of the ST-300, TH350, TH200, 200-4R, Saginaw 3 and 4 speed, Muncie 4 speed, and Dearborn three speed trans are all the same length as installed in the car (though crossmember location is different on the 200-4R). The automatics and all manual transmissions except the M22 use the same front yoke on the driveshaft in the A-body also.

 

Front yoke should be fine.
Driveshaft, shorten and balance. Measure after every thing else including the dew diff is in place. And the weight of the vehicle is on the rear wheels.
Mount, yes I think it will fit.
Crossmember needs to go back. The frame has room to move it around, but the ST300 is a short trans and the 2004r is much longer. I can't say without measuring, if it will fit.
I've run into situations where the x-member mount location also had to drop about an inch for tunnel clearance. You should look at the mount pads on the two tranny's to see if they are similar height. You could fab a new x-mem or check on Summit, they have several new ones available if needed.

There is much more that you didn't ask about, Dipstick and tube, TV cable mounting and pull geometry, electrical wiring and switches for TCC lock up solenoid and even speedometer drive gear ratios. Not to mention a shifter that was designed for a 2 speed, now operating a 4 speed trans.

Any questions?

 

Already bought a flexible stainless steel dipstick tube...
speedo gear i will have to by one of the adjustable boxes from summit.
i already bought the b&m tcc lock up box...
the shifter will work but the stops ar gonna be a problem...figured i would handle that when i get there...but if you know what i will need ahead of time let me know.
see this is the problem. People tell me the driveshaft does not need cut and others say usually 1/2 inch...while others say to measure...i was planning on measuring for sure. But i wanted to hear if anyone else had just put the same shaft back in and it worked?
First time i heard about geometry...hhhmmm good thought though....i will try to find a flat place and measure the angle, then go back once its done to make sure it has not changed drastically. Thanks for the insight guys.

 

I merged your 2 duplicate threads.

 

You might want to check out Bowtie Overdrives site... the new installation instructions cover a lot of the questions you ask, also shows where to measure and such.

 

The geometry I refer to is simply the length of pull for the TV cable to control the trans. 2004r and 700r4 need 1.75 inches of cable travel between idle and WOT.
You'll want to locate or fabricate, an attaching point for the cable stud, on the linkage, that provides this linear travel through an arc. And locate a mount bracket for the cable housing that allows proper adjustment from that point.
Kit's are available to simplify this for Holley or Edelbrock carbs, I don't know of any for Q-jet.

If any of my previous advice was inaccurate I sincerely apologize, I have not done the 300 to 2004r swap that you are doing. Others who have done this exact swap may have better advice. Most of the experience I have involves swapping in 700r4's in place of a TH400 or a manual. I am presently completing the TH400 to 700r4 swap on a '68 GTO with 428ci Pontiac motor, using an adapter plate kit. If/when I do the swap on my own '65 Vistacruiser (455ci/TH400) I'll use the same method.

 

Shiftworks may have the detent plate for your shifter to change it from the 2 speed to the 4 speed 200r4.
Bowtie Overdrive may have the kit to add to your carb to attach the TV cable.
As far as the drive shaft, measuring it is the safest bet, although if the transmissions are the same length, you shouldnt have to change anything other than the trans crossmember. Your frame should already be drilled for this, just unbolt it and slide it back.

 

If you have to change the driveshaft lenght, its not because of swapping from a Jetaway to a 200-4R, it would be because you changed the rear end (possibly).

I still used my 2-speed column shifter, used a Kugel Komponents adjustable kit to account for the larger angle of shift shaft swing on the 200-4R. A little adjustment to get the detents in the trans aligned with the "gates" on the column shifter is all it took. Works great, but nobody makes a PRND321 indicator for a '68 Cutlass speedo, so I have to count the notches. No big deal for me since my Sun Tack blocks the view of the PRNDL anyway.

DEFINATELY invest in a TV-EZ kit from Bowtie Overdrives. And their OD lockup relay kit is pretty reasonable and works great.