just to let everyone know, I DO NOT OWN A TURBO REGAL, BUT WISH I DID! with that stated i need to know any info on a th250 tranny swap. i want the 4r and i know this is a good place to ask question concering that and other things we might have in common. i have a 83' cutlass calais and it has the junk th250 and junk gears. so i NEED to put a 4r! my last car had the 4r and i loved it, nice around town and on the highway. i plan on putting in a D5 converter while im in there so i get a better launch, and some better gears, but lets get back to the qeustion. whll the 250 swap out to the 4r. i relize i will have to figure out how to lock up the converter and i plan on doing that through the forth gear switch. but will the r4 fit? im not sure so i am hopeing someone hear could give me a awnswer! thanks!
Well, not being familar with the 250 (I've never seen one), take this for what it's worth.
The 200-4R is very similar dimensionally to a short tail THM350. It will bolt right up, but you may have to change the transimission cross member and have the drive shaft adapted to the correct length. Also, not sure about the yoke, but the 200-4R is about the same as a 350.
Hi Don, I can help you with this. You can do it two ways. First check your frame on the left side rail and see if you have two mounting locations for the trans crossmember. 1983 was a split year and you may only have one location on the left. If you have two than you can use a crossmember from a car that has the THM200-4R(it doesn't make a difference on engine type) and make sure you use the mount that comes with the X-member. 200-4R and 250C can use the same driveshafts. They are the same length. If your frame only has the one mount on the left side you should be able to use the existing crossmember. I have never done a swap this way so I am not 100% sure this info is correct but the mount pad on the trans may be in the same location. If at worst you might be able to enlongate the hole in the X-menber to bolt it up.Also the cross-bar on the shift/neutral safety switch is different so make sure you change that too.
All I could add is that the th250 and the th350 are dimensionally the same. I swapped the 250 out of my wife's Limited and the 350 was a drop in.