2004r Conversion

jonstringer · 05-06-2008, 02:12 AM

I have a 1972 Olds Cutlass S w/ a 455 ci, TH350 transmission, and a 2.73 open rear. I want to convert it to a 2004r OD transmission with a 3.73 posi. I'm sure quite a few of you have done this conversion, so I go to you for advice.

1. From tranny core purchase, to HD rebuild, what am I looking to spend?
2. What fabrications will need to happen to retrofit this transmission in the th350s place. I have heard that they are the exact same size, and that no mods are necessary for this swap.
3. Will the console shifting linkage work properly with the 2004r?

I am all ears. I can learn from your success and failure in converting your car. Thank you for any advice you may have.

jon

68conv455 · 05-07-2008, 07:30 PM

I'm still in process with the swap. But I can tell you some things.
1. For a core, general concensus is the 86 or 87 buick GN trans with the BRF valve body. At the end of the GN run, most of the bugs were worked out making these the best of the stock tranny's. Because of their popularity, cores will cost you. I've seen cores for 200 and running transmissions for 500. I've got a so called good running 1985 GN transmission for starters. I plan on debugging the car with the stock transmission before investing in one built to withstand abuse. I'm leaning toward CK performance for my built unit. Just the trans will cost close to $2K.
2. The trans is the same length as your TH350 and the Yolk is also the same. You will need to move the cross member toward the rear of the car. My 68 cutlass already had factory holes in the frame for this. You will need to get a TV cable and appropriate mounting bracketry/plate for your carb. You will also need to incorporate a convertor lock-up switch. I've heard some people say the TC bolts don't fit through the 455 flexplate. Mine fit fine.
3. I've seen shift detent plates made for stock style floor shifters. The kits come with new D N R etc strip also. I'm not sure where but if you look around I'm sure you'll find one. I've deleted my column shift due to headers and am going with a B&M Megashifter.

On a side note, a 3.73 may be scary on the street with the 2004r. First gear is lower than your TH350 so the 3.73 will actually feel higher when you combine the two. I've planned a 3.55 rear for mine.

Good luck.

05-06-2008, 02:12 AM	#1 (permalink)
jonstringer Member Join Date: Feb 2008 Location: Austin, TX Posts: 33	2004r Conversion I have a 1972 Olds Cutlass S w/ a 455 ci, TH350 transmission, and a 2.73 open rear. I want to convert it to a 2004r OD transmission with a 3.73 posi. I'm sure quite a few of you have done this conversion, so I go to you for advice. 1. From tranny core purchase, to HD rebuild, what am I looking to spend? 2. What fabrications will need to happen to retrofit this transmission in the th350s place. I have heard that they are the exact same size, and that no mods are necessary for this swap. 3. Will the console shifting linkage work properly with the 2004r? I am all ears. I can learn from your success and failure in converting your car. Thank you for any advice you may have. jon

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05-07-2008, 07:30 PM	#2 (permalink)
68conv455 Senior Member Join Date: Oct 2007 Posts: 119	I'm still in process with the swap. But I can tell you some things. 1. For a core, general concensus is the 86 or 87 buick GN trans with the BRF valve body. At the end of the GN run, most of the bugs were worked out making these the best of the stock tranny's. Because of their popularity, cores will cost you. I've seen cores for 200 and running transmissions for 500. I've got a so called good running 1985 GN transmission for starters. I plan on debugging the car with the stock transmission before investing in one built to withstand abuse. I'm leaning toward CK performance for my built unit. Just the trans will cost close to $2K. 2. The trans is the same length as your TH350 and the Yolk is also the same. You will need to move the cross member toward the rear of the car. My 68 cutlass already had factory holes in the frame for this. You will need to get a TV cable and appropriate mounting bracketry/plate for your carb. You will also need to incorporate a convertor lock-up switch. I've heard some people say the TC bolts don't fit through the 455 flexplate. Mine fit fine. 3. I've seen shift detent plates made for stock style floor shifters. The kits come with new D N R etc strip also. I'm not sure where but if you look around I'm sure you'll find one. I've deleted my column shift due to headers and am going with a B&M Megashifter. On a side note, a 3.73 may be scary on the street with the 2004r. First gear is lower than your TH350 so the 3.73 will actually feel higher when you combine the two. I've planned a 3.55 rear for mine. Good luck.