Not since the heyday of the Flathead have Ford engines been as popular in street rods as they are today. Thanks to the performance reputation established by the muscle-bound powerplants, like the Smeding Performance 347 incher under the hood of our Shadow Rods roadster pickup, more and more small-blocks are wearing a Blue Oval instead of a Bow Tie.

Just as like the evolutionary process the engines have gone through, there have been significant changes in automatics since the days of the two-speed Ford-O-Matic and the contemporary transmissions from Ford are some of the best. To get a handle on the various contemporary gearboxes that are commonly found behind Ford engines, we turned to the experts at Gearstar Performance Transmissions. Here's what they had to say.

For street rod applications there are two categories of Ford transmissions to be aware of: the three-speeds, which include the C4, produced since 1964, and the C6 produced since 1966; and the four-speed overdrives, which we are going to concentrate on, the AOD, AODE, and E4OD.

The C4 and C6 transmissions were known in the '60s and '70s as dependable transmissions that could be modified for Ford-powered cars used on the strip as well as the street. And thanks to better technology, advanced bands and clutches, improved shift kits and the availability of super-hard internal parts, they can be built even better than ever before. Of course the same technology can be applied to the AOD, AODE, and the E4OD overdrive transmissions.

In 1980 Ford introduced the AOD, beating GM to the showrooms with an automatic overdrive transmission by a year. The new four-speed transmission contained basic design elements of the C4 and cast-iron FMX, highly modified and conjoined. Designed to mate up to the 5.0L/302ci engines, the AOD can be easily adapted to the Ford Y-block and the FE series engines. Thanks to high-performance parts and modifications by Gearstar they can meet the demand for a dependable, efficient, high-performance, overdrive transmission for the true Ford believers.

Over the next few years Ford redesigned many internal components to meet increasing demands upon their AOD transmission and in 1992 the AOD became the AODE, electronically controlled transmission. Since then Ford has continued to refine components in the AODE, and many of these updated components will retrofit to the AOD line. Combine the latest generation of Ford factory components with those available from the aftermarket (shift kits, clutches, bands, shafts, drums, and torque converters) and Gearstar has everything to build the perfect AOD or AODE.

Although the AOD and AODE are stout transmissions, for high-torque, big-block applications (429, 460, and up) the E4OD is the way to go because with Gearstar's modifications this transmission is capable of handling 800-1,000 hp and all the torque that goes with big-block horsepower.

Based on a highly modified C6, the E4OD is unique in that it has the overdrive component added to the front or input side of the transmission. Since its inception, E4ODs have always been an electronically controlled transmission and require a "stand-alone" computer to control gear changes, shift points (rpm), and shift feel (line measure rise) and Gearstar will supply that as well. In fact, everything you need to get your Ford in overdrive is a phone call away.