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This page is for informational purposes only. We no longer recommend or provide support for AOD builds/swaps other than specifically for our valve body kit.

Performance Guide

Section 4: What to look for when purchasing

What to Look for When Purchasing Used AOD-E/4R70W and AOD Units

If you are searching for a used AOD-E/4R70W or AOD transmission to swap into your project vehicle (or for a performance buildup), this section should prove helpful.

In addition to the specific tips below, please be aware that all AOD and AOD-E/4R70W transmissions can have either a seven or eight tooth speedometer drive gear machined into the output shaft. Generally speaking, vehicles with 2.73-1 axle ratios may have an eight tooth output shaft. If unsure, it would be wise to remove the extension housing and count the helical teeth. Depending upon tire size used, an eight tooth output shaft may make speedometer correction difficult for axle ratios lower (numerically higher) than 3.27-1. Unfortunately, output shafts cannot be changed without disassembling the transmission.

When looking for an AOD-E/4R70W transmission, the following tips apply.

  • The bell housing pattern is different for a 4.6L or 5.0L/3.8L/4.2L engine and the two are incompatible. The two case types can be distinguished by looking at the starter flange area. If the starter has three attaching bolts, the case fits only 4.6L engines. A two-bolt starter indicates a 5.0L/3.8L/4.2L compatible case (casting number may begin with "F4ZP", not available before 1994).
  • Does the unit have a wide or standard ratio gear-set? This requires you to know the original application or remove the pan and inspect the ring gear through a drain-back slot. AOD-E transmissions built through 1995 share the same standard gear ratios as the AOD, except for the 1994-95 Thunderbird, 1994-95 F and E series trucks, 1995 Full Size Cars, and the 1993-95 Lincoln Mark VIII. 1996 and later units are all wide ratio transmissions.
  • Valve bodies for 1992 cars have a different shift pattern ("P-R-N-OD-D-1", like an AOD) than other AOD-E/4R70W units ("P-R-N-OD-2-1"), because these cars had no Overdrive Cancel Switch.
  • 3.8L V-6 AOD-E/4R70W transmissions have only one less clutch plate than V-8 units and, with our valve body kit, are at least as strong as any AOD. If you are planning to replace the clutches in your transmission, two new pressure plates (less than $20) from the Ford parts department will make it equal to a V-8 AOD-E/4R70W. Unlike the AOD, you needn't avoid buying V-6 versions of the AOD-E/4R70W transmission.
  • Some trucks (and possibly a few Lincolns) use a one-inch-longer output shaft than the Mustang and other vehicles.
  • Many AOD-E/4R70W units (especially later and wide ratio units) use an extension housing with a larger output bushing. This housing accepts a slip yoke with a larger outside diameter. This is not a major problem, as the slip yoke or extension housing can be changed and all output shafts share the same 28-spline profile as an AOD or C-4 transmission. An AOD-style extension housing can easily be bolted onto an AOD-E/4R70W. The large bushing housing bears a casting number beginning with "F3LP" for the standard length and "F3UP" for the long unit. The small standard length housings are marked with either "F2TP" or "E0AP". The small bushing long version is marked as "E0TP" or "E0LP" and is probably only used with the AOD transmission.

If you are seeking an old-style AOD, the following tips apply. Also, remember that most of these transmissions are quite old and crusty now, so choose carefully.

  • Try to avoid pre-1988 models without rear-lube enhancement. It is likely that planet bushing damage may have already occurred, mandating expensive new gear-train parts as well as an updated output shaft.
  • 1992-93 E and F series trucks (those with AOD's and not E4OD's) contain the strongest production AOD transmissions. Included is the two-inch wide overdrive band (part of the Motorsport Wide Ratio Kit, or available as a separate conversion kit from Baumann Engineering for close-ratio applications, and highly recommended for full-throttle use of overdrive) and the now-famous "A" overdrive servo.
  • All Thunderbird SC supercharged V-6 transmissions contain the "A" servo (its original application) and the strong H.O. V-8 style clutches, but still use the 1.5-inch overdrive band.
  • In situations other than those listed above, any 1988 or later V-8 AOD transmission (steer clear of the base V-6 units) should prove adequate for most AOD buildups. Be warned, however, that most Lincolns and some trucks use a one-inch-longer output shaft than the Mustang and other vehicles. Naturally, you will have to re-use your vehicle's manual lever and external linkage.