Solid billet aluminum transmission mount for GM TH350, TH400, 700R4, 4L60E, and 4L80E builds that takes out the flex a rubber mount lets through under load.
Wheel hop on launch, a clunk from under the console when you hit the throttle, or a shifter that moves on its own when the car loads up: on a GM drag car or LS swap, those usually trace back to a rubber transmission mount that is soft, torn or simply too flexible for the power. ICT Billet 551404 is a solid aluminum mount for the common GM tailhousing pattern, so the back of a 4L60E, 4L80E, TH350, TH400, 700R4, Powerglide or T56 stays put on the crossmember instead of rocking under torque.
The engine mounts carry the front of the powertrain, and the transmission mount carries the back. Novak lists the 4L60E at 146 pounds dry and 162 pounds full of fluid, so the mount supports real weight, and it also resists the twisting force the transmission sends back into the chassis every time it multiplies torque. A rubber mount lets that housing rise and twist. On a street truck that is fine, it soaks up vibration. On a car making big power, the movement changes driveshaft angle in the middle of a launch, which can set up wheel hop and hammer the U-joints. A solid mount removes the rubber so the transmission cannot move relative to the crossmember.
With the car safely supported, pry gently between the tailhousing and the crossmember and watch the rubber. Then have a helper shift between drive and reverse with the brake held. Movement of more than a small amount, cracks, or rubber leaning off its plate mean the mount is done. Be sure the clunk is not internal, though: a harsh engagement can feel like a broken mount, and our 4L60E shift problems guide explains how to separate hydraulic harshness from a driveline knock. For the failures a hard-launched 4L60E tends to have, read the 4L60E Camaro common problems guide.
ICT lists 551404 for Chevy TH350, TH400, 700R4, 2004R, 4L60E, 4L65E, 4L70E, 4L80E, 4L85E, 6L80E, 6L90E, Powerglide, T56, TR6060 and the Muncie 4-speed. What these share is the mount pad, not the vehicle, so measure your tailhousing and crossmember before ordering. ICT notes all five holes are in a straight line; compare that to the bolt pattern on your old mount. The mount bolts to the factory location and does not require driveshaft or crossmember changes when your crossmember is set up for this pattern. Not sure? Send us your vehicle, year and transmission. More 4L60E parts are on our 4L60E parts page.
Building a swap from scratch? The LS flexplate adapter kit handles the front end of the installation, and a 4L60E shift kit firms up the shifts to match a car that is meant to launch hard.
| Fits | GM TH350, TH400, 700R4, 2004R, 4L60E, 4L65E, 4L70E, 4L80E, 4L85E, 6L80E, 6L90E, Powerglide, T56 Magnum, TR6060, Muncie 4-speed |
| Type | Solid mount (performance / drag racing) |
| Material | Aerospace-grade billet aluminum, machined in Wichita, Kansas USA |
| Install | Bolts to the factory crossmember location, no driveshaft or crossmember mods |
| Note | Solid mounts transmit more driveline vibration than rubber; race/strip choice, not a comfort upgrade |
| Dimensions | 7.3 x 4.9 x 2.1 in |
| Brand / Part Number | ICT Billet 551404 |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes, more than rubber. With no rubber to isolate it, more driveline vibration and noise reach the floor. It is meant for drag and high-power use, not a quiet daily driver.
It uses the common GM mount pad pattern with all five holes in a straight line. Compare that to your existing mount and crossmember before ordering, or send us your vehicle details.
ICT states it is machined in Wichita, Kansas from 6061-T6 billet aluminum produced in the USA, and it comes with mounting hardware.
ICT specifies 37 lb-ft for the mount bolts.
Only if the clunk comes from mount movement. A harsh engagement caused by line pressure or a worn U-joint will remain, so diagnose the source before replacing the mount.
