I have been trying to research the difference between th350, th400 and 200r4 mounting location. My car has a th350, which took a crap. Now I'm debating between th400 and 200r4.
According to some posts here, if I were to mount th400 I would need to move the crossmember back about an 1". But when I look at the picture below, transmission mount is over 5" farther back for th400 than th350. Also I've read that 200r4 is a bolt-in in place of th350, but on the picture it shows mounting location is identical to th400.

My question is how far back do I need to move the crossmember if I was to install th400 or 200r4 in place of th350.

Thank you.

 

The T350 the xmember is forward. Although the T350 and 200R4 are the same basic length the Xmember shares the same position for both the T400 and the 200r4, approx., 6" back. Look at the measurement on the left side of each transmission pic, 27 15/16 for the 200r4/T400 vs 22 1/4. If you change to a T400 you will need to modify/replace the driveshaft.

 

Thanks Eric, that's what I thought. I have been researching this since last night, I was getting confused by guys saying that crossmember needs to be moved only an inch or so.

 

There is zero confusion about this, as documented in the drawing in your first post. The mounting pad on the TH200/250/350/Jetaway are all 22 1/4" back from the block face. On the TH400 and 200-4R, that dimension is 27 15/16". 27 15/16 - 22 1/4 = 5 11/16" further back (yes, this is why you needed to stay awake when the teacher was talking about fractions...).

If your car is 1967 through 1977 (for the A-body cars), the holes are already located in the frame from the factory. Frankly, I always wonder why people fret over this. Install the engine, install the trans, bolt the crossmember to the trans, and that's where the crossmember needs to be. The only issue on an A-body car is the e-brake cable, since moving the crossmember requires different front and intermediate cables. Get the cables for the same year/body with a TH400 and that problem is solved.

 

Thanks for chiming in Joe, I was awake during all my math classes and that is why I am asking the question.
The reason I was confused was not the fractions but the previous posts from members here stating "you only need to move the crossmember an inch or so", but my math calculations (cause I stayed awake) were giving me a different result. 5 11/16" is a lot more than "an inch or so", at least over here where I live. I have seen 3 or 4 posts stating exactly that "an inch or so", and that is why I was confused. I would quote but I don't wanna put the members on the spot.

The reason I fret over this is my ARH headers. Upon installation one of the (many) problems with them is that header collector flange ended up right under the crossmember, to solve that I extended the collector few inches. So if I have to move the crossmember back few inches it might be more work, cutting the collector, extending the exhaust. Now I am looking at more work than initially planned.

This is why I was confirming the exact mounting location. Also it wouldn't be the first time that something was out of norm on the Oldsmobile.