[cormy1]

I've decided to get serious about installing a 4 speed in my 66 289 fastback. I dont understand the differences between the two transmissions and would perfer to have the cheapest 4 speed install possible. I just drive the car for pleasure and not all that much. Is there reallly that much of a difference if so..could I be educated??

Please no 5 speed recomendations!

 

[68fastwilliams]

If your looking for the cheapest route, then the T10 is the way to go since they are about 1/3 the price of a top loader. Just don't power shift it to much as they have a tendancy to bend shift forks durring this operation. But if you only drive the car once and awhile then it should hold up just fine for you.

 

[66 6]

The T10 will be less expensive as long as you get the complete shifter rods and everything for a MUSTANG. If not you will pay!!!!!

 

[Guest]

I've heard synchronizers are weaker on the T10 also.

 

[cormy1]

Could you explain that?

 

[C7Mustang]

Yes, T-10s are cheaper but as others have said ONLY if you get all the Mustang-related gear that you need to install it and you don't need any internal parts for it. I had a T-10 with a ruined speedo drive gear once (a common occurrence because people making conversions stick their 3-speed/automatic speedo cable gears in the trans and don't realize the four speed requires a reverse cut gear) and I couldn't find a replacement anywhere. Ended up paying big $$$ to a transmission shop for a good used one.

So if you go with a T-10 make sure it is a long tailshaft version with a Mustang shifter setup. Just like the Toploader, T-10s can be had in close or wide ratios. Depending on your rear axle ratio you may not like starting out in first with the wrong type trans (low gears + wide ratio = very low first gear, high gears + close ratio = very high first gear).

As far a general driveability goes, you won't notice any difference inside the car driving either a T-10 or a Toploader if both are in equally good shape.

 

[Midlife]

T-10's can probably be had for $100-200, whereas toploaders go for $600+. That's almost a false economy, as most used T-10's are sold because the synchro's go out, they pop out of gear, and parts are sometimes hard to get ahold of. Toploaders, on the other hand, are almost bulletproof, are well supported (parts, etc.). The two are identical in fit and function, and all external parts are transferable.

If you can find a T-10 still installed and can test-drive it, then that's the way to go.

 

[BornInAFord]

My T-10 lasted over 400,000 miles with one rebuild and is still going strong for the new owner. I really liked its very smooth shifting (toploaders have a reputation of being a little more "notchy"). With the rebuild came a redesigned slider and no more grinding between 1st and 2nd nor popping out of gear when letting off the throttle.

Is it as stong as a toploader? No, but few transmissions are. It is probably similar to the 85-89 T5, though, and was put behind some of Ford's stoutest early 60s big block mills and behind the 65 Shelby. Would I have bought a toploader or a T10 if I was replacing the whole unit? Probably a wide ratio toploader because of its better gear spacing--my T10 had the first three speeds as a short ratio and the final very wide (2.54, 1.89, 1.51 and 1.00:1 from 1st to 4th, respectively) so it seemed to waste a gear. I went with a T5Z and have never looked back. I do miss the buttery shifts, though.
Daniel

BTW, the speedo gear should be the same as a toploader of the same era, IIRC.

 

[68RCodeConv]

If it was me I would go ahead and put in a T5. The extra gear sure comes in handy. It lets you have the best of both worlds by running a steeper rear gear and still have low rpm highway cruising.

There is a good chance that any "cheap" T10 or toploader will need rebuilding. There goes your budget - you're past used T5 territory.