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JEGS Transmission Crossmember for GM TH400
555-640603
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G-Body Crossmembers
Installation Notes:
- If installing on a 1978-1983 G-Body you will need part number 555-54718 frame extension. This piece is designed to replicate the longer driver side frame rail of the 1984 and later GM G-Body cars giving you the proper mounting locations for this crossmember.
- Some 1983 Hurst Oldsmobiles were originally equipped with a 2004R transmission and will not require this frame extension. If you are unsure, 1984 and later models will feature two mounting locations for the transmission crossmember approximately 14 in. behind the front set of mounting holes.
- Crossmember is designed for 1978-1988 G-Bodys that were originally equipped with an SB-Chevy. Does not fit Cutlass Supreme models or El Camino. Engine and transmission swaps may require some additional modifications & fitment of components. Hardware is not included.
Specifications:
Crossmember Finish
Black powdercoated
Crossmember Material
Steel
Quantity
Sold individually
Transmission Crossmember to Frame Bushing Included
No
Transmission Mount Included
No
Bolts Or Studs Included
No
Mounting Bracket Included
No
Mounting Bracket Included
No
Amount of Drop
Stock
Width
45.84 in (1164.34 mm)
Shipping Weight:
13.1
Package Height:
48
Package Depth:
9
Package Width:
6
These transmission crossmembers are made from 1-1/2" x 2-1/2" x 0.120" rectangular tubing. The double hump design clears dual exhaust when using exhaust kit 555-30556 and headers 555-30060. Clears Dual Exhaust & Allows Transmission Swaps
Does JEGS 640603 fit your vehicle?
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1984 OLDSMOBILE CUTLASS CALAIS
- Liter: 5.7
- SubModel: BASE
- Aspiration: NATURALLY ASPIRATED
- CUI: 350
- Engine Type: V8 ( 5.7L / 350 )
- Engine Vin: N
1984 CHEVROLET MONTE CARLO
- Liter: 5.7
- SubModel: BASE
- Aspiration: NATURALLY ASPIRATED
- CUI: 350
- Engine Type: V8 ( 5.7L / 350 )
- Engine Vin: J
1978 PONTIAC GRAND PRIX
- Liter: 4.9
- SubModel: SJ
- Aspiration: NATURALLY ASPIRATED
- CUI: 301
- Engine Type: V8 ( 4.9L / 301 )
- Engine Vin: W
1984 OLDSMOBILE CUTLASS SUPREME
- Liter: 5.7
- SubModel: BASE
- Aspiration: NATURALLY ASPIRATED
- CUI: 350
- Engine Type: V8 ( 5.7L / 350 )
- Engine Vin: H
1982 OLDSMOBILE CUTLASS CALAIS
- Liter: 5.7
- SubModel: BASE
- Aspiration: NATURALLY ASPIRATED
- CUI: 350
- Engine Type: V8 ( 5.7L / 350 )
- Engine Vin: R
1979 CHEVROLET MALIBU
- Liter: 4.4
- SubModel: ESTATE
- Aspiration: NATURALLY ASPIRATED
- CUI: 267
- Engine Type: V8 ( 4.4L / 267 )
- Engine Vin: J
1981 OLDSMOBILE CUTLASS SUPREME
- Liter: 5.7
- SubModel: LS
- Aspiration: NATURALLY ASPIRATED
- CUI: 350
- Engine Type: V8 ( 5.7L / 350 )
- Engine Vin: N
1980 OLDSMOBILE CUTLASS
- Liter: 5.7
- SubModel: BROUGHAM
- Aspiration: NATURALLY ASPIRATED
- CUI: 350
- Engine Type: V8 ( 5.7L / 350 )
- Engine Vin: N
1980 PONTIAC GRAND PRIX
- Liter: 4.9
- SubModel: BASE
- Aspiration: NATURALLY ASPIRATED
- CUI: 301
- Engine Type: V8 ( 4.9L / 301 )
- Engine Vin: W
1983 CHEVROLET MALIBU
- Liter: 5.7
- SubModel: CLASSIC
- Aspiration: NATURALLY ASPIRATED
- CUI: 350
- Engine Type: V8 ( 5.7L / 350 )
- Engine Vin: -
1980 CHEVROLET MONTE CARLO
- Liter: 4.4
- SubModel: LANDAU
- Aspiration: NATURALLY ASPIRATED
- CUI: 267
- Engine Type: V8 ( 4.4L / 267 )
- Engine Vin: J
1980 OLDSMOBILE CUTLASS CALAIS
- Liter: 4.3
- SubModel: BASE
- Aspiration: NATURALLY ASPIRATED
- CUI: 260
- Engine Type: V8 ( 4.3L / 260 )
- Engine Vin: F
640603 is rated
out of
5 by
16.
Rated 5 out of
5
by
Mark penz from
Fit my 1985 GMC Caballero (El Camino)
The description says it does not fit the El Camino but it fit my 1985 GMC Caballero (El Camino perfectly. I am replacing my original transmission with a 2004r and this crossmember fit perfect. No modification needed. My car does have the driver side frame extension. If your does not then this may not work in your car. Less than half the price of competitor's crossmember
Date published: 2019-12-29
Rated 5 out of
5
by
Blake M from
Perfect fit
My 88 Monte Carlo SS has a rebuilt 200 4r trans bolted to a 70s era 350 HP 350, 305 is in the dumpster. Several custom exhaust shops in my area recommended this crossmember. Bolted right in. Welds look good, time will tell.
Date published: 2019-07-12
Rated 5 out of
5
by
Mojomunki from
Great price and fit!!
Installed on my 86 Monte carlo ss to add dual exhaust. Works for the 200r4 trans as well as the turbo 400.
Date published: 2019-06-20
Rated 5 out of
5
by
hot rod 81 from
built to fit
bought this product last month was going to fab. it but the price was right and super fast shipping
Date published: 2017-04-11
Rated 5 out of
5
by
TREXXTMAXX from
exact fit
easy to install, exact fit, no modification needed
Date published: 2016-11-28
Rated 5 out of
5
by
Sparky1 from
Good product.
Went right in my grand Prix. Was able to bolt th400 right in place using this cross member. Dual exhaust humps will make the exhaust a breeze.
Date published: 2015-12-12
Rated 4 out of
5
by
MGillam from
Good bang for your buck
Despite the warnings about not fitting El Caminos I saw examples of people making it work so I figured for the price it was worth a try. It bolted up with no issues. I haven’t dropped the drivetrain in, but at least I can verify that with the appropriate frame expansion it will bolt between the frame rails and doesn’t interfere with the body. It doesn’t look like it has as much space as the competitors for a large exhaust system, but it should be quite a bit better than stock
Date published: 2019-06-11
Rated 4 out of
5
by
WALKERZ from
Product fit well and gives the correct clearance for a true dual exhaust system
Date published: 2018-01-22
I have a 86 t-type regal sbc/turbo 400trans will this crossmenber work.
Yes, this should work for your application.
Date published: 2018-11-07
Will this work with a 1985 cutlass supreme I am putting a turbo 400 in it with a big block of not what one can I use?
No, this will not work with the Cutlass Supreme. You will need to make a universal kit work - https://www.jegs.com/i/Trans-Dapt/969/4549/10002/-1
Date published: 2018-06-12
Have a 1978 cutlass Calais I put a 2004r trans and 305 in this week. Will this cross member work
Yes, this will fit your Oldsmobile Cutlass Calais.
Date published: 2018-06-08
Is this the right crossmember for a 1981 malibu with 200-4r transmission?
Yes, this should work for your application.
Date published: 2018-06-08
I have a 86 regal with a 6.0 ls with a 200 4r tranny. But i dont see a listing for a crossmember and that specific tranny. But I Have looked at other products. And noticed that the th400 and 200 4r. Are the same is that true with this crossmember?
This crossmember should work in your application.
Date published: 2018-05-30
Do you have one that would fit a el camino
No, you will need to modify this or use a universal crossmember on your El Camino.
Date published: 2018-05-24
You offer a TH350 & TH400 G-Body crossmember, 2 different part numbers. However in both pictures it shows the same trans. mount support bracket. A TH350 mount has a single center bolt hole, a TH400 mount has 2 bolt holes spaced 1 3/4" from center-center?
The transmission mount has 3 holes and should fit either transmission.
Date published: 2018-05-15
I have a 1981 Malibu it had a v6 now will have 5.3 ls that will sit where existing bell housing was. Will I need an extension for this or will it bolt right in?
The crossmember will bolt in, you way have to adjust for the transmission mount pad depending on the TH400 you use to connect to the LS series engine.
Date published: 2019-09-30
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