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Well bad news for me is my original TH350 tranny for my 69 bird was stolen from the dealership that did the rebuild. Just got it done and with a B&M Shift kit in it all ready to go and it turned up missing. They feel they know who stole it but video didn't catch it so I doubt I will ever see it again. Frustrated is beyond words but they are reimbursing me nicely. My question for now is I have a TH400 I took out of a 73 Grand Prix years ago. It looks like it will bolt right up to my 350 Engine block but are there other factors I need to consider if I have them use that one. Such as tranny length, kick down, cross member and etc. I have read vague things to all of this but I am not a tranny person and it raises lots of concerns for me if it will work. It looks like the slip yoke is heavier duty but will still connect to my same driveshaft too. Its been many many years since I took this out of the car but could a '73 TH400 have overdrive? I seem to remember it did. Thank for any advice on this. Always appreciated.
 

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Th400 is bigger heavier stronger, if you have a crazy engine I say do it if not I say 350 again

400 does not have o.d.
Iirc you need to change the drive shaft yoke and possibly d.s. length

Same cross member but uses the farthest back holes in the frame

And you may need to drop in the engine trans as a unit

These are what we did when I swapped from 2 speed auto to t.h. 400
 

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None of the 3-speed trannies have overdrive. All have 1:1 3rd gear ratio.

If I were you, I'd stick with the TH350. That way you won't have to change yokes or crossmember. Don't know what you can spend on a trans, but, mild rebuilds are less than $1000. and good beefed up versions are around $1500, or maybe a little less. :yes

http://www.jegs.com/i/JEGS-Performance-Products/555/60305/10002/-1?parentProductId=

http://www.jegs.com/i/JW-Performance/564/20205B/10002/-1?parentProductId=2930413

http://www.coanracing.com/Catalog.asp?ProductDetail=1573
 

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I'd be pretty upset if my original 350 went missing, I think I'd want a period replacement and parts and labor free on rebuild. Hopefully they are taking care of you to your satisfaction.
 

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TH400 will have a different Crossmember, Should verify the tailshaft on the Grand Prix is a short one. (I'm not familiar with the Grand Prix setup, but if you are getting a new driveshaft that probably doesn't matter.)

Also, the camaro crossmembers are different from the firebird crossmembers for the TH400. This was due to the BBC motors and getting fitment around the steering components.

You will need a Firebird TH400 crossmember.
 

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"...Should verify the tailshaft on the Grand Prix is a short one. (I'm not familiar with the Grand Prix setup..."

All the '69-up GP's I've seen, used a short tail. But a long tail can work. On the 1st '68 Bird I bought, I used a long tail TH400, made a simple crossmember, changed yokes, and had the driveshft shortened. Hey, at that time, I didn't even know there was a long or short tail. Somebody told me I needed a TH400. So I went to the junkyard and bought one. It just happened to be a long tail, out of a big car. Worked great tho, and won lots of races. :smile22:
 

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I say put a Lenco in it....LOL
 

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Discussion Starter · #9 ·
Thanks for the feedback! Yeah they feel its an inside job as no one knew it had a shift kit in it and a fresh rebuild except other employees. One employee was let go for theft of this nature and they feel he may have nabbed it. They promised a good replacement but your right in that I should and will push for a period replacement. That's the frustrating part as it was the original transmission to the car. Unless they want to absorb all the work and expense to make the TH400 fit and work properly I am going to push for the TH350. I will let you know how I make out on that:). Thanks so much for the advice! Always appreciated.
 

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Need to know if anyone knows about the aftermarket th400 crossmember, i see them listed 2 ways , 1 is big block chevy as mentioned above, 1 is sbc and all firebird

Here is my issue one is cheap and one is like 3 times the price

Depending where you look this one says it fits https://www.jegs.com/webapp/wcs/stores/servlet/SearchResultsPageCmd?Ntt=+189-CM01-67&requestYear=&storeId=10001&catalogId=10002&langId=-1&year=&make=&model=&submodel=&engine=&Nrpp=&No=&persistYmm=false

But some sellers say same one is only for bbc
 

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Unless im reading wrong looks like the chevy bb th400 crossmember and the sbc/firebird th400 crossmember are the same except the bbc bracket for the trans mount is offcenter by 1/2"

If this is true ill buy the cheap bbc one and move the mount lol
 

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I need pics of th400 shift cable brackets mounted on a 69, im having issues and see mu l tiple parts listed, i bought a new bracket but there are 2 listed, the cable says same for 350 and 400

Looks like there are 2 shift levers listed
Pic of what i have going on, either i cant use my shift lever or i bought the wrong bracket, im thinking its the lever becuse now the lock rod from the column does not reach
Pics
 

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I found this in a google search, pic is from the first gen firebird site , can so eone confirm this is the correct setup for th400 and a 69, if so it is of course the other cable mount bracket listed lol
Here is the pic
 

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Bracket pictured above is correct best i can tell, i got one today and its all installed

My final issue with the shift cable seems the repop cable i have is slightly longer on the trans end so the cable wont hook to the lever by 1/4" ?

Im thinking i will try to drill a second hole in the cable since the adjustment on the shift lever is maxed out
 

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']['exXxas']['itan
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This is what you need
 

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Thank s i got an original from a friend, my oer reproduction cable is actually snapped inside the housing

So the th400 x member came, box says 67-69 firebird, it is offset to drivers side and seems the tab is forward see pics, it does fit the frame perfect

Imjust going to move the tab where i need it
More pics
Should the bottom of the trans pan be exactly parallel with the sub frame?
 

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Went ahead and moched up and welded, looks like i moved it about an inch to the drivers side, and a little to the rear, i did make a paid of spacers for the sides to fill the gaps
 

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Are the motor mounts new? Did you loosen up the motor mount bolts and try to pull the trans over? Its pretty common for the motor/trans to shift when old mounts sack out.

that box shows Camaro and firebird. I was under the impression the fire bird cross member was different. Something to do with the way the exhaust was run on the camaros for the big block. Idk.
 

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Big block chevy the endine and trans mount are shifted to pass side 1"

Sbc and firebird are same trans x member, this part number shows for bbc or sbc depending where u buy it lol

I agree it should fit since box said it

This car had no motor mou ts on frame amd no drivetrain. When i bought it, just cant remember if there was adjustments, either way its in now
 
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