Speedway GM Manual Trans to Flathead V8 Adapter - GM Clutch

Now you can easily mount a modern, fully synchronized GM manual transmission to your early Ford or Mercury Flathead V8 engine! This is a great way to get better driveability and improved performance from your 1932-48 Ford or 1939-50 Mercury Flathead.

This aluminum adapter permits the use of most GM-style 3-, 4- or 5-speed Muncie, Borg Warner, Saginaw and Early GM Style T-5 manual transmissions (Not Compatible With: later 1993+ S10/NV1500 units) behind your Flathead V8s. Adapter is used in conjunction with Flathead flywheel and a GM-style clutch fork and bearing (or Speedway bearing and arm kit 916-29510).

• Fits 1932–1948 Ford and 1939–1950 Mercury Flathead V8 engines.
• 1948 trucks and 1949–1953 Ford/Mercury engines require the OEM 3" adapter bellhousing.
• Not compatible with Canadian Mercury “French block” engines; verify block type before purchasing.
• Mounts common GM-style manual transmissions, including Muncie, Borg Warner, Saginaw, and T-5.
• Uses Throwout Bearing and Clutch Fork Kit (#916-29510) for GM transmissions, or can also use GM stock-style hydraulic throwout bearings.
• Compatible only with Borg & Beck or diaphragm-style pressure plates.
• Includes a pilot bushing adapter.
• Designed for use with the original Flathead flywheel; re-drilling the pressure plate bolt pattern may be required.

Learn more about using T5 transmissions with these adapter plates by reading our tech article. Adapting a T5 to a Ford Flathead V8.

Item Details

Uses Borg & Beck or Diaphragm-style clutch

NOTE - If you are still using the stock rear axle assembly, an open-drive conversion will be required. Depending on the year and style of your differential, Speedway Motors offers several kits to assist with this conversion:

• Part # 919-1105 – 1935–48 Ford 6-Spline V8 Banjo Rear End Open Drive Conversion Kit (fits ’35–’48 rear axles with common 6-spline pinions)
• Part # 919-1106 – 1935–48 Ford 10-Spline V8 Open Drive Conversion Kit (fits ’35–’48 rear axles with common 10-spline pinions)
• Part # 919-1111 – 1928–31 Ford Model A Open-Drive Driveshaft Conversion Kit

Once the conversion is complete, a custom driveshaft will need to be installed. Speedway Motors offers Part # 910-383, a Universal Steel Custom Length Driveshaft Kit with a 3-inch OD. Other diameter and material options are also available to accommodate a wide range of applications.

• 1932-1948 Ford Flathead V8s
• 1939-1950 Mercury V8s

NOT COMPATIBLE with Canadian Mercury “French block” engines

GM T-5 Installation Notes (PDF)

• 1" thick mounting flange
• Adapter is 3-7/8" thick front-to-back
• Bellhousing mount holes are drilled for 3/8" bolts
• Transmission mounting holes are tapped 7/16-14
• 8-1/4" center-to center top bolt holes
• 9-1/8" center-to-center bottom bolt holes
• 4-7/8" center-to-center bottom bolt to top bolt, either side
• Pilot bushing adapter I.D. is 0.590", .660" O.D., and length is .790"