The 4 cylinder T5 has a 3.97 first gear and a much reduced torque capacity. It may last a day or a year depending on its original condition and how you drive it. The information I have is that the pilot bearing you need is for a Ford Ranger diesel from AutoZone part #14672.
The computer harness is different on 4 cylinder and V8 cars. You will need a 91 V8 Mustang harness for a plug and play swap. The 92 & 93 V8 Mustang harneses relocate the fuel pump relay to under the Mass Air meter and may require some extra effort in the wiring department.
The 5.0 cars use a cable much like the throttle cable for the clutch. See
http://www.fordracingparts.com/download/instructionsheets/FordInstShtM-7553-B302.pdf for installation instructions & pictures for the cable and quadrant assemby. You will need the Adobe Acrobat viewer which is also a free download –
Adobe - Adobe Reader download - All versions
Code on the rear axle is 3L73 for a 3.73 with traction lock. The "L" designates the rear axle as a traction lock. Use a 87-88 T-bird Turbo Cope rear axle and you get an 8.8 axle with traction lock, 3.55 or 3.73 gears and disk brakes.
Do the 87-88 T-Bird Turbo Coupe rear end swap!
Auto trans 87-88 Tbird Turbo Coupes come with 3.73 gears and manual Turbo Coupes come with 3.55 gears. Cost is $125-$300 for the rear axle. Add another $100-$200 or so to complete the brake upgrade.
I choose 3.55 since I do more highway driving. Both ratios have 10 5/16" disk brakes with vented rotors as standard equipment.
It takes 2 guys the first day to get the old rear end out and the new one bolted in place. It takes 1 guy another whole day to do the brakes.
You will need a several sets of fittings, I recommend that you get them from Matt90GT's website,
87-93 Mustang 5.0 Brake upgrade pages. Improve your 60-0 times!.
Read Matt's instructions thoroughly, everything you need to know about the brakes is all there. You need to be patient and follow all the internal links, and there are many of them. You will need 2 fittings in the rear to adapt your old brake tubing to the TC disk brakes. The fittings go between the steel tube and the caliper
brake hose. You will need another set of fittings to make a 2 port to 3 port adapter. To make life simpler, just buy the kits from Matt. You could piece them together, but it's not worth the time unless you work at an auto parts store with all the fittings ever made.
You will need to drill the quad shock mounting holes 2” below the holes drilled for the Turbo Coupe mounting points. The bolts are metric, so don’t loose them or the nuts. A 15/32” drill should be about the right size unless you have access to metric sized drill bits. Going without quad shocks is not an option unless you have aftermarket parts to soak up the wheel hop.
You will need a proportioning valve, Summit has one for $40 + shipping.
You will need a kit (FMS makes the part) to gut the stock proportioning valve, Summit also has that, about $10.
You will need a new master cylinder, see Matt's site and make you choice. I used a 94-95 Mustang master cylinder. Note that rebuilt 94-95 Mustang master cylinders do not come with a reservoir. That means a trip to the junkyard and some more money spent.
Your brake pedal may be very hard and almost impossible to lock up the brakes. I had to replace the front calipers with 73 mm calipers from a 91 Lincoln Mark 7 to get the braking performance up to par.
Bleeding the brakes will require 2 people and some coordinated effort. I don’t recommend using you wife or girlfriend to pump the pedal – they get offended when you yell at them. I used a homemade power brake bleeder constructed from a garden sprayer and some fittings from Home Depot. It cost about $25 and was worth every penny. See
how hard is it to bleed brakes? - Mustang Forums at StangNet for details and pictures.
See
Mustang Central.net FMS M2300K Brake Install for help with the emergency brake. The red words link to some very useful photos on how to modify the handle. The stock setup tends to lock up and not release properly.
All in all I have been very pleased with the results.
Identifying a Turbo Coupe rear axle:
1.) Measure the rotors - a TC disk brake uses 10 5/16" vented rotors.
2.) Measure the length of the quad shock mount arm and compare it to the mount on your existing stock axle. The TC quad shock mount arm is about 8" long if I remember correctly.
3.) Measure the distance between the axle flanges and compare it to stock. The TC rear axle assembly is 3/4" wider per side, or 1 1/2" wider for both sides.
getting a 5.0 HO and t-5 for a 91 notch 4 cyl 5 speed...i have been told the differences for swaps are this- input shaft is 1/4" shorter/longer on MT's, gearing is different...? plus this, i have a 89 lx 5.0 HO T-5 car, the cable goes from the firewall down and there is a ball that hooks directly through bellhousing to the clutch fork, on my 91 lx 4 cyl it goes same up to bellhousing but then to a kind of pulley system, almost to pull the fork the other way...the bushings are SHOT so its metal on metal, not driving the car now due to the fact i need a new quadrant kit and cannot find this bushing kit!!! going to swap in a 302/347 this spring, how much difference is there in trannys? cant find VIN codes for rear axle but i know i want the 3.73 8.8 posi, anyone know that letter? AND, putting a 140 speedo in place of 85, need that gear i know, as far as harnesses go, im guessing it couldnt be as easy as unplug ECU on 4 cyl and plug in 8 cyl box...? dont have a harness yet for 8 cyl, 
