Small block to big block trans cross member doesn't work after swap?

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U may also have a truck mount bolted to ur crossmember and I believe they are a little taller than a car mount Kim
I agree

As an example;
My 68 Barracuda is wearing a 73 up spool mount crossmember. On it, is a long-tail A833 which has the same trans mounting point as any pass-car 727. My spool mount is shorter from the trans mounting-surface to the bolt-tunnel, than yours is.
 
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So I purchased this car with out an engine. The trans was still installed. It was a small block 727. So I took my motor home big block 727 and had it rebuilt and used the tail shaft off of the small block trans.

When I go to bolt it up, the cross member only goes one way, but the body of the trans/bell housing hits the firewall and the tail end of the trans is tipped too far upward to get the driveshaft on, let alone in operating position.

I loosened up the two bolts that hold the round rubber mount to the trans and that gave me a little play, but it's still not close. The round rubber mount comes off the transmission and angles back towards the tail end.

So take a gander at the photos, what's not right? The cross member will only bolt up one way, so that's not adjustable, and the round rubber mount is already angled the direction it would give me the most clearance. I've read all the cross members were the same so what gives???

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Couple things going on here and you need to be very clear about the front end of the trans and where it’s hitting. Also show some pictures of that.
I can see in the third and fourth pictures of your original post that you have a later truck style output housing, the part your insulator is bolted to. I have that same housing and trans crossmember currently installed in my A-body, although mine is a small block right now, and is a later 1975 model year.
I previously had this same crossmember and insulator, and the same driveshaft with my previous big and 727 trans in this same 75 A-body.
I will add a picture of my crossmember, although it’s from a different angle so hard to compare for sure, but shows yours is installed correctly.

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Couple things going on here and you need to be very clear about the front end of the trans and where it’s hitting. Also show some pictures of that.
I can see in the third and fourth pictures of your original post that you have a later truck style output housing, the part your insulator is bolted to. I have that same housing and trans crossmember currently installed in my A-body, although mine is a small block right now, and is a later 1975 model year.
I previously had this same crossmember and insulator, and the same driveshaft with my previous big and 727 trans in this same 75 A-body.
I will add a picture of my crossmember, although it’s from a different angle so hard to compare for sure, but shows yours is installed correctly.

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Here is a picture on the driver's side of where it was hitting. It's the body seam, rubbing some black paint off. I fabricated the ears on the spool rubber mount to extend it about 1" - 1.5", moving the trans away from the firewall. This will at least get me real close to where it should be.

If anyone else has a barracuda with a big block that could give me some type of measurement from the mounting surface of the trans to the firewall that would be very helpful.

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Here is a picture on the driver's side of where it was hitting. It's the body seam, rubbing some black paint off. I fabricated the ears on the spool rubber mount to extend it about 1" - 1.5", moving the trans away from the firewall. This will at least get me real close to where it should be.

If anyone else has a barracuda with a big block that could give me some type of measurement from the mounting surface of the trans to the firewall that would be very helpful.

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That should move your engine forward and cause engine mount and header fit issues IF the rear trans mount was already in the correct location. We’ll have to see when the engine goes in.
 
I had the same issue when I put a later model 318 and 727 from a tradesman 200 van in a 67 B'cuda that was originally slant 6.
The 67 A-body was still much like the 1st gen' A-body in a few places. That cross member wasn't relieved on both sides for dual exhaust pipes, and the 727 hit the panel seam. Trans mount didn't line up either. My experience was back in 1982 so I dont exactly remember everything I did. I recall air hammer to fold that seam away. A different cross member, It still wasn't the spool mount type cross member. I might have tuned it around to make the mount line up with that trans and hogged out the bolt holes.
For what its worth, factory went through the same chit to put a big block and 727 in the 67 model. The car came off the assembly line and went to a seperate bay so the engine and trans could be hammered in. All of this was sorted so a-body could easier get a big block and dual exhaust in 68 up. Good luck with yours.
 
The 67-62 and 73-76 crossmembers all interchange to a certain extent. Only difference is the 67-69 cars used larger 1/2 inch bolts. 70 up cars used 3/8s bolts. So a little modification is in order. U may also have a truck mount bolted to ur crossmember and I believe they are a little taller than a car mount Kim
Yes, the mount appears to be from a truck, van(same as the one on my 72' B-300 van) and I believe possible an E body, but for sure, not an early a-body (I also have a 69' 340 dart and it has the posted block mount). I agree with most of you, get the correct cross member. Should not be difficult to acquire.
 
Don’t Frankenstein it or overthink it. Use the correct cross member mount and tranny mount for the year of the car. The big block 727 tranny fits the 67 and up A-body floor pan with plenty of clearance.
 
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