Dual Carbs

Source:  http://www.modelaparts.net/webbcat.htm/catp63.htm

Custom: Model A Rear Differential

Stock Model A Rear Differential Banjo

DIY Welded Fabrication of a Model A Quick Change Rear End

Source:   http://www.jalopyjournal.com/forum/showthread.php?t=649046&showall=1

Model A Ford - Mitchell Gear Splitter OverDrive System

Mitchell Gear Splitter

Introductory Video for Installing the Mitchell Gear Splitter

Mitchell Gear Splitter available in 27% and a 33% O/D ratio, The internals are simple...and in underpowered cars like model A's when being "toured" in the mountains, the ability to split-shift is a nice feature. After they are 'worn in' a bit, you can shift them on-the-fly without even depressing the clutch pedal, just lift and flip it in and out of O/D as need be. If I had to give a negative, I would say that the extra gear shift lever protruding from the floor can be a nuisance --especially in cars that have tight floor spaces.

Source URL's: 

Installing an OverDrive: http://www.management-advantage.com/media/DVD-OverdrivePreview2010.wmv
Short Story: http://www.365daysofa.com/post/10584346803/day-346-getting-our-hands-dirty 

Mitchell OverDrive: http://www.management-advantage.com/media/ModelAFordOverdrive.jpg