I'm going to order a 200r4 for my car , I know pretty much what it will take to go from the Jetaway to the 200r4 thanks to the many post here .
But last weekend while I was changing the ring and pinion , I noticed that I have run the exhaust very close to the crossmember . It turns inward toward the X ( Magna Flow system ) just after the crossmember , so I'm going to have to do some surgery to the exhaust to move the crossmember back .
With that said , just how much farther back does it have to move . How many inches .
I would like to do the exhaust modifications before the trans is done .

 

You'd have to move it the same distance as the crossmember - I'd add an inch for extra clearance.

 

I said that !
How far back does it have to go in inches ?

 

The crossmember will sit in the same spot as would be needed if the car had a TH400 trans. I'm pretty sure it would use the rear-most holes in the frame to bolt the crossmember to the frame. My car isn't here now for me to look to compare.

 

Your frame already has the second set of holes for the TH400 position of the crossmember. Just measure the distance between the two sets of holes.

 

Yes , which set of holes?

 

Frank,

I am working on a 65, I just did exactly the same change, 200R4 and magnaflow complete exhaust from headers back. I know this is not an accurate answer to your question, first of all did you bolt your exhaust up or weld it? have you cut the magnaflow set up anywhere? MAKE SURE you do not cut the ends that mate with the collectors, if you do you will be bringing the 45 degree bends closer to the crossmember and stand a chance of not clearing at all. We used a trans mount from a 68-70 big block chevelle, for a few different reasons that was specific to my build. I DID have to drill new holes in the frame, I can take pics if you would like, but you might be able to tell in my build thread what I am talking about. If it were me I would wait and fit the exhaust until after the tranny is in if you can. If I can help you in any way dont hesitate to ask.

 

Does the st300 (Jetaway) and the th350 use the same mount location ?
If so my answer is 7"

 

I found the measurements I was looking for ,
If anyone else needs them .
http://www.transmissioncenter.net/Tr...asurements.htm