JEGS
GM TH400 Transmission Crossmember
555-640603
Product Q&A
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G-Body Crossmembers
JEGS 555-640603 Transmission Crossmember Features:
- The double-hump design allows dual exhaust upgrades for your vehicle
- Black powder-coated steel for strength, great looks, and long life
- Must have upgrade for transmission swaps
JEGS 555-640603 Transmission Crossmember Installation Notes:
- If installing on a 1978-1983 G-Body you will need part number 555-64718 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 cross member approximately 14 in. behind the front set of mounting holes.
- Crossmember is designed for 1978-1988 G-Bodys that were originally equipped with a Chevy small block engine.
- 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.
FAQ
Is a transmission crossmember important?
- Yes, a transmission crossmember is crucial for maintaining proper alignment and support for your transmission in your car ot truck.
What size bolts attach a TH400 to a crossmember?
- Use appropriate size bolts as specified in the TSM (technical service manual) for the transmission being used. Depending on the year and application they could be either Metric or SAE thread.
What is a TH400 transmission compatible with?
- The TH400 was introduced in 1964 and produced through 1990 and is compatible with various GM (General Motors) applications, including Buick, Cadillac, Chevrolet, GMC, Oldsmobile, and Pontiac Model Cars and Trucks. It was also used in Jeep applications, including Jeepster Commando, Jeep Wagons and Pickups from 1969-1979, and Jeep CJ7 Models from 1976-1979.
Specifications:
Part Type
Product Line
Amount of Drop
Stock
Bolts Or Studs Included
No
Crossmember Finish
Black powdercoated
Crossmember Material
Steel
Mounting Bracket Included
No
Package Depth
9.00
Package Height
48.00
Package Width
6.00
Part Category
Replacement Parts
Part Fitment
Direct Fit
Quantity
Sold individually
Shipping Weight
13.10
Transmission Crossmember to Frame Bushing Included
No
Transmission Mount Included
No
Width
45.84 in (1164.34 mm)
640603 is rated
out of
5 by
34.
Rated 5 out of
5
by
Quiet storm from
Gbody cutlass bbc
I have a 86 cutlass with 454 bbc with th400 fit perfectly
Date published: 2023-07-17
Rated 5 out of
5
by
Mike R from
Nice GBody crossmember
Well made, fit perfectly in my 1985 442 with TH200-4R. A good value and got the job done with my new 3" exhaust system.
Date published: 2022-09-06
Rated 5 out of
5
by
Ummm from
Fits 1985 El Camino.
Used under a 1985 El Camino when changing from a TH350 to a 200-4R. Currently still running original single exhaust with no issues. When installing make sure the transmission is lifted just high enough to slide the mount in. Don’t raise it to the floorboard or you will fight, curse and want to send it back prematurely.
Date published: 2022-06-23
Rated 5 out of
5
by
Tony from
Gbodys
Very nice quality fits my 1985 Oldsmobile Cutlass very well with a 6.0 LS and turbo 400 trans
Date published: 2022-05-19
Rated 5 out of
5
by
Turbojack from
Cross Member
Great crossmember that fits good and at a good price. This is well made and should last a long time.
Date published: 2022-05-06
Rated 5 out of
5
by
SS BEE from
Worked perfectly
Bought this crossmember for my 86 SS Monte Carlo an It fit perfectly no modifications needed
Date published: 2022-05-01
Rated 5 out of
5
by
CSScibelli from
Great fit with 200 4R
Good quality product for the price. Wish they still had a Jegs branded exhaust system to go with it. I used this on an 86 Monte Carlo SS with a 200 4R. They really should list this as for TH400 and 200 4R. It was a perfect fit.
Date published: 2022-04-21
Rated 5 out of
5
by
ghostfacek from
Fits stock trans!
Was unsure when purchased but fits 200r4 with minor modifications
Date published: 2021-11-01
Will this fit 1985 buick regal with tci powerglide
The Jegs 555-640603 crossmember does not fit a Powerglide transmission.
Date published: 2024-04-22
How close will this be on my 62 Oldsmobile with a TH400 transmission?
The Jegs 555-640603 G-body crossmember does not fit a '62 Oldsmobile.
Date published: 2024-04-15
Will this fit a 1984 Oldsmobile Cutlass Hurts old with olds 307 and TH200 4r trans?
The Jegs 555-640603 crossmember does not fit an '84 Hurst Olds.
Date published: 2024-01-18
Will this fit a 200-4R tranny in a 1988 monte carlo ss? I see mixed answers on here some say it fits and some say no...thank you
The Jegs 555-640603 cross member is designed for TH400 transmission swaps in 1978-88 Malibu/Regal/Cutlass/Monte Carlo/Grand Prix/GN.
Date published: 2023-08-24
Will this work on a stock 1980 Monte Carlo with 305/200R?
The Jegs 555-640603 crossmember does not fit a 200r4 transmission.
Date published: 2023-06-23
I have a Oldsmobile 442 87 2door with a 6.0 Ls swap and 4l60trans will this fit
The Jegs 555-640603 crossmember does not fit 2-door Cutlass Supreme models.
Date published: 2023-01-12
I have a 1982 cutlass calais with a 355/200r4 will this crossmember work?
The Jegs 555-640603 crossmember will not fit a 2-door Cutlass. It is only compatible with 4-door cars on an Oldsmobile.
Date published: 2022-12-09
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
Some parts are not legal for use in California or other states with similar laws / regulations
Motor Vehicles
WARNING: Motor vehicles contain fuel, oils and fluids, battery posts, terminals and related accessories which contain lead and lead compounds and other chemicals known to the State of California to cause cancer, birth defects and other reproductive harm. These chemicals are found in vehicles, vehicle parts and accessories, both new and as replacements. When being serviced, these vehicles generate used oil, waste fluids, grease, fumes and particulates, all known to the State of California to cause cancer, birth defects, and reproductive harm.
Tools:
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Electrical Cords
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