Originally Posted by Nova250-6
A couple things I wonder about are:
-Can I use the same torque converter?
-Will I have to get a different crossmember?
-Can I use the same column shifter?
Any help or advice is appreciated.
No, you can't use the same converter. Different input shafts and the 200-4r is a lockup converter.
You probably won't have to get a different crossmember. The 4r will bolt to your existing crossmember, but the mount is about 4" further back than it was on the 350. Many GM cars (but I don't think the Xbody) have multiple holes drilled in the frame to accomodate this exact thing. For instance a Monte Carlo might have had a TH350, but an Olds Cutlass might have a 4r. GM simply equipped both cars with extra holes in the frame to make things easier. You might have to get clever depending on what your frame looks like, but its pretty straightforward.
You can use the same column shifter, but of course the letters and numbers won't line up. You also might find that the throw of the shifter isn't far enough to go all the way down to first. I went the opposite way; from a 200C three speed to a 350 and I noticed that it was much shorter between detents so you may have the opposite problem. The solution is pretty simple; just get the whole set of shifter arms and pivots from the 4r from the column down to the tranny. Its a simple matter of length of the lever
A couple other considerations:
-also get the TV cable and bracket from the carb of the donor car. The 350 uses a vacuum signal and no cable. The 4r uses a cable but no vacuum.
-Double check your driveshaft, but you should be able to use your stock driveshaft. The overall length of the two trannys is within like 1/8" so you should be fine, but double check the splines and diameter.
-You'll also need the proper speedo gear.
-You're also headed for a big mismatch with a .67:1 overdrive and 2.73 gears. Your highway RPMs with the overdrive and 2.73 will be 1500 rpms. If you want to drop a little highway RPMs, I would add the 4r tranny and swap to 3.73s... seriously. The final drive will make those 3.73s act like 2.50s and your highway RPMs will be more like 2000. I dealt with a 2.73 rear and a 4r for a couple months before I yanked the rear in favor of 4.10s. At 75 mph it wouldn't stay in OD, it kept hunting in and out because it was lugging.