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Has anybody swapped out a 3 speed M/T for a 5 speed M/T? It will be going in my 1968 289. I am just curious how much alteration I'll have to do to get it to mesh up, and if anybody has the experience from it (like "don't try it", or "worth the time")...
 

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do your home work---b/w t-5 came in about 150 different p/n---lengths--gear ratios ect---you need to know what your low gear ratio is know and the o/d ratio in the new trans---with out changing rear gears , i'd guess a .7 od would be max--a .80 better
then there is speedo gears (elect or mech0 and shifter locations---the s-10 is great for a foreward location but the early mech speedoi gear version are getting tough to find--a shop in texas is modifying late elect s-10 housings to mech speedo gears--well done
if you can find a good trans rebuilder he can swap pats around to make a neet trans---my 47 sedan runs a 1986 nissan turbo 300zx trans ,late s-10 tail housing ,94/94 w/c input shaft with carbon fiber sincro ring---3.35 low gear with a .8 o/d with 3.55 rear gears--gets you about 72 mph @ 2000 rpm---with a carb engine you should keep the rpm up enough to get good fuel signals to the carb--otherwise you are running on the idle circut
have fun---doctordesoto
 

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Discussion Starter #3
Thanks for the quick reply. This car is my first project, and I've never done anything that wasn't a direct (OEM/original) replacement before. Where do I go to do my "homework" and find out more about modification? Does anybody know if I put in a 80's model 5 speed from a mustang, would that work?
 

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It's doable. there are a few guys here who have done it. Consider a few things first, what type clutch you want - hydro or standard, and one thing to consider is that the shifter opening will have to be enlargened a bit to the rear, as well a a different trans cross member. You may be looking at shortening the driveshaft too. Be sure to keep the yoke from the donor car so you have the correct one. http://www.mustangmonthly.com/howto/mump_0307_how_to_install_a_five_speed_in_vintage_mustangs/viewall.html
 

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Re: 3 speed M/T to 5 speed M/T - Google is your Friend

There have been hundreds of articles on this conversion, both in print and on the Internet. The "trick" is to realize that, whether or not a Cougar owner wants to accept the fact, the Cougar is "just like a Mustang" (from the engine by to the rear seat footwells); and there are a lot more early Mustangs than Cougars out there being converted to a T5 (or TKO) manual transmission.

So, just go to Google and enter in "Mustang" and "T-5 conversion". There are at least 10 pages -at 50 results per page- on the topic. Some are basic how-to articles like the previously mentioned Mustang Monthly article, some are vendors offering kits from basic to all-inclusive, with clutch activation parts, crossmembers, and transmissions.

One thing to understand right off; the model T5 that comes closest to fitting an early Cougar will come from a 79-93 "Fox-body" Mustang. From that assortment, look for transmissions from the later-model cars; as a "factory-stock" T5 from a 1979 four-banger Mustang may or may not stand up to your 289, depending on driving habits.

You could even do an "Advanced Search" right in this Forum and find some threads on the subject. It's very common with today's prices.
 

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It's absolutely worth it. I had a 4 speed in mine the day I bought it and immediately put a 5 speed in it. Overdrive works wonders for your gas mileage and lets you keep up with everybody else's highway speeds.

Yes, you need a 5 speed out of a fox body Mustang. If you can get one that has "WC" on the side with the serial number you're even better. That is the "world class" T5 and is heavier duty. I have a basic T5 in mine behind a built 351 without breaking anything yet (that was related to the T-5 being weak...)

You also need the conversion kit that has the cross member and adapter plate. You use your original bellhousing, clutch fork, and clutch. I just had to replace the throwout bearing and clutch fork in mine (because they weren't when the T5 was swapped in) and it feels super smooth now. I don't see a need for going with the cable clutch unless you have clearance issues. You will also need your driveshaft shortened about an inch or so.

But, yes, it is certainly worth whatever hassle you have to go through to get it in there!
 
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