7.5 to an 8.5 or any direct posi rear

[83 Regal]

Dimensionally the same, but internals are different. The GN's had all of the necessary upgrades, but good luck finding one. Then the late 442's & SS Monte's were next in line. Most 200's were in underpowered G-bodies or grocery getters. If you have one from a plain Jane Monte Carlo, then it will work, but if you plan to put the wood to it on a regular basis with a 450+ ft/lb 455, then you'll need to upgrade it. Post the 3 letter abbreviation on the tag of the one you have.

Would it be the CRF ? on this 200 4r ?

 

[64nailhead]

KZF -- Olds 442/Hurst
CZF -- 85-88 Monte SS
CRF -- 85-88 LG4 305 powered Monte Carlos/Pontiac Grand Prix
BRF -- 86-87 GN/T-Type/Turbo Regals
BQ -- 84-85 GN/T-Type/Turbo Regals
BR -- 83 Model T-Types
TAF -- 89 Turbo Trans Am
OZ -- Hurst Olds
OM -- Olds 350 Diesels
OG -- lds 307
BY -- V-6 252 Cars
AA and AP -- Cadillac's

I didn't compile this list , but rather grabbed it from a Monte Carlo site. But this a relatively complete list for G-bodies. There are more codes than these as 200's were used in full size wagons and trucks as well. You'll need a couple of parts replaced/upgraded if you intend this thing to live behind your 455 for heavy footed driving. But for normal cruising it will be fine.

 

[Ve8r]

Personally I would go with a 400 trans and 8.5,8.8 ford, or ford 9 inch on the rear end.
I shredded two 200-r4 trans and multiple 7.5 rear axles in my Cutlass behind a mild 455 olds.
This was with street tires.

My Cutlass currently has a 400 trans and will get a 8.8 swap in the near future.

Your mileage may vary as they say.....

 

[Opie Knievel]

Yes 200r4 is a Buick/olds/Pontiac/Chevy bolt pattern bellhousing

I did some research the other day when I was looking to buy a 200-4R. In addition to the many varieties of different internals, there are 3 different bellhousing patterns. 1 fits Chevy engines, 1 fits Buick, Olds, Pontiac engines and 1 is a multi-fit case that fits Chevy, Buick, Olds and Pontiac engines. Make sure you get one that will fit your engine.

 

[83 Regal]

I have a 10 bolt stamped 1249518 does anybody have a decoder for this? can't quite make out the other three or number on the other side of housing...G1N or something and the head of it is pear shaped

 

[oldsmobile joe]

I did some research the other day when I was looking to buy a 200-4R. In addition to the many varieties of different internals, there are 3 different bellhousing patterns. 1 fits Chevy engines, 1 fits Buick, Olds, Pontiac engines and 1 is a multi-fit case that fits Chevy, Buick, Olds and Pontiac engines. Make sure you get one that will fit your engine.

I've always heard of a 200-4r trans with a chevy only bell housing but I've never seen one. is this true?

 

[L67ss]

I've always heard of a 200-4r trans with a chevy only bell housing but I've never seen one. is this true?

I've seen mebbe two

 

[83 Regal]

I should have a kit that allows you to bolt with some minor welding a 98+ zr2 S10 rear, 8.5 3.73 posi disk brake rear in a g body with stock control arms springs ect. Just need to get some corvette/firebird wheels with 7" backspace.

Do you still have your kits? And how much ?

 

[81cutlass]

Do you still have your kits? And how much ?

I am still working out the design and fab. I have the lowers done, I just need to get the upper brackets finished. My machine program is written I just need to get it cut out. Probably tomorrow or 2 weeks from now. No firm pricing yet but $350 is my estimation.

 

[Steveshow]

You could put 8.5 28 spline axles and an aftermarket posi in your existing housing. They will take quite a bit of abuse.

I still have a previous project 87 Regal with a 455/TH400 with a 7.5 rearend. If you do not intend to use slicks they work fine.

If you can find a used posi and gears from a 93-02 Camaro or Firebird, then just buy replacement Turbo Regal/Grand National axles.

As far as I know, most failures of the 7.5" rear are due to axle failure, not ring gear failure. If the swap above in fact works, this would be a cheap upgrade!