This was too good to just pass up and too much to just repeat here. That’s coming up next for my ’70.
So from http://www.fordmuscle.com/archives/2000/09/t5swap/index.php, here is some very good information on upgrading your Mustang’s (Ford’s) transmission.
Overdrive transmissions are a great thing. They enable you to significantly improve the gearing and acceleration of your car, while maintaining gas mileage and highway cruisability. Unfortunately overdrives, manual or automatic, weren’t offered in Ford vehicles until the late 70’s. But that doesn’t mean you have to be stuck with the non-overdrive C4’s. C6’s, and manual 4 speeds of the 60’s. Swapping in a late-model overdrive transmission, namely the T5 manual and the AOD automatic, is a straighforward swap for 289, 302, 351 equipped cars. In fact on most early Fords, the swap is so easy it makes you wonder if Ford was thinking ahead. In this article we’ll go over what it takes to swap in a T5 tranmisssion into an early Ford. In future articles we’re go over an AOD swap for early Fords, and also an AOD to T5 swap for late-model Mustangs.
Swapping into early Mustangs, Falcons, Mavericks, and Pintos is easy because the hole in the transmision tunnel for the shifter is in about the same spot on all the cars. The swap is also easy for Fox body cars such as the Granada.
For other Fords, namely the full-sized cars, the swap is a bit more difficult because the engine is placed farther forward in relation to the driver. Ford
If your car is currently equipped with a non-overdrive manual transmission (Ford 3spd, 4spd, or Toploader) the swap is as simple as a clutch job, you can use your existing clutch and flywheel, but you’ll need a crossmember and possibly a slip yoke and driveshaft as mentioned below. For cars with automatics you’ll need to first install a clutch pedal and round up the clutch activation parts (either manual clutch linkage or a cable operated clutch.)
We’ve seen the T5 in several Falcons and Comets originally equipped with column shifters. The owner had to punch a hole in the transmission tunnel and fabricate a longer shifter and/or replace the bench seats with bucket seats. Most Ford cars sold with automatic transmissions have factory stamped holes in the firewall for the clutch pushrod or cable. Usually a hard tap from a mallet will knock the stamp out.
For Bronco and Ranger owners, jamesduff.com sells adapters to bolt the T5 to 2.9L and 4.0L engines.
Where to find a T5?
While it is best to shoot for the 90-93 T5 due to its increase torque capacity, you shouldn’t pass up a good 83-89 T5, espeically if you’re engine is not heavily modified. We’ve found that T5 strength and longevity is more a factor of its condition and mileage rather than it’s torque rating. A used, high mileage, Cobra T5 will probably shift poorly and give out much sooner than a earlier T5 that came out of grandma’s car. The T5 in Project 11.99 was bought from a wrecked 1990 Mustang 5.0 with 50,000 miles. We’ve had it in the car for nearly five years now, over 400 passes at the strip, and it shifts as crisp as it did on day one.
By the way, always take the bellhousing and block plate if they are available. The T5 swap can be done two ways, using a T5 bellhousing or using an early Ford manual bellhousing. It is much easier and cheaper to use the T5 bell, we’ll explain why below.
What to pay?