Seriously, somebody educate me on the trans!

I’m fairly new into owning and working on my 68 XR7, but I know I absolutely despise the 3 speed automatic transmission. It constantly is breaking and it drives like…well, a damn 3 speed. Where can I buy a good replacement automatic transmission that is a 4 or even 5 speed? I am so tired of this crap granny. I have no clue what to replace it with or where to purchase a new 4 or 5 speed automatic. Somebody help me in my Ignorance.

Sorry Texas, I don’t have a good answer for you, but I know there are several folks on the forum here who know all about that sort of thing. Hopefully someone will chime in with a direction to go for information.

The swap to a 4 speed aod is a well-documented option and probably your best bet.

Nothing wrong with a C4 transmission other than the lack of an OD. This can cure that:

Whats your budget and overall vision for your car? That is really going to be the question to narrow down your options.

besides being only 3 speeds the C4 is not a terrible transmission. what about replacing it with a quality rebuild and making sure its setup correctly? Obviously that does not solve the lack of overdrive if that’s a deciding factor.

To try and answer your question without knowing much information about how much you want to spend or how deep you want to get into modifying your car I would say look at the AOD swap. You may have to tread around on some mustang sites to see swaps being done but thats ok since cougars and mustangs are similar enough for much of the info you will need. Hit up the vintage mustang sites and dig around. Alot of those guys modify their cars in similar ways so its a great way to research your options as well.

I installed a AOD in my 67 and love it, but no matter what you settle on, if it has an overdrive gear you will have to change your rear gear to a higher number.

So I just want a reliable semi daily driver with decent power. It sounds like yal are suggesting doing a C6 AOD swap and maybe a 3.55 rear gear ratio to compliment it? My budget is a few thousand but obviously if I can save money I want to, I just want it done right. I hate driving it on the highway right now so I think a 4 speed could solve that issue.

Two downsides to the AOD are 1) weird shift pattern: OD-D-1 instead of the more familiar D-2-1, and 2) dealing with TV cable adjustments. But gaining overdrive is well worth it. Here’s some info/advice from back when I did the swap into my 68: ideally, get everything from the same parts car so you know everything is correct. For instance, there are several flexplates that will see to “fit” but they have slightly different offsets and if you install the wrong one, it will quite literally destroy your transmission within the first few minutes of driving. Don’t ask how I found that out. Also, any used AOD that you find now is already so old that you can assume it needs to be rebuilt. Factor that into your budget. In addition to the flexplate and transmission itself, you’ll need a modified crossmember, transmission mount, and cooling line adapters, all of which are available from various Mustang vendors. You will have to either swap in an AOD yolk onto your driveshaft (or shorten your existing C4 yolk, which is easily done) and you may need to shorten your driveshaft itself (although I did not have to do that on mine). Your existing shifter will work with a custom or modified linkage. And you’ll need the TV cable (unlike the C4, which uses a vacuum modulator to shift, the AOD uses hydraulic pressure controlled by a special cable connected to the throttle arm on your carburetor). There are various hot rod shops that sell TV kits for just about any carburetor. Oh, try to get an AOD from a Mustang or other car with a floor shifter. One from a column-shift car will work, but you’ll need to pull the pan off transmission and flip the shifter arm around (not difficult, but drippy).

I’ve got a 70 that I haven’t been able to drive yet, but I did swap my FMX for an AOD. I never messed with a trans before but the swap was fairly easy, I still need to get the correct crossmember as I ended up modifying my stock one to clear the AOD. Other than that it’s all in, fairly easy, shortened driveshaft, and many Lokar parts for it.

I assume the same is true for the C-4, but the bellhousing bolts from my FMX wouldn’t reach through the mounting surface of the AOD since it is thicker, so I had to order some longer bolts for it, and the top most passenger side bolt required a little denting of the firewall/tunnel to get it in there correctly.

Lokar has an adjustable shift linkage, shifter arm swap, TV Cable kit that comes with a ball park adjustment tool, and a bracket that bolts to the rear driver carb stud that is for holding both throttle cable and tv cable. Good parts and pretty good instructions, fairly easy.

If you’re just looking for something easy and done very often it would be the AOD.

There may be nothing wrong with the C4 but spending 3K for OD on an old tech transmission doesn’t compute for me. Spend that much and you could probably install a ten speed instead.

Options and comparisons.
I considered the AOD and the GV unit for my 460 but decided for the price and trouble a lower 1st gear in my C6 and a mid range rear gear was the best option. I can burn a lot of gas before that GV would be paid for.

Exactly. Overdrive, schmoverdrive. Just run those RPMS up like we did back in the day. Not gonna hurt it.


Just finished the majority. Need to put in the AOD for the c4 and redo the windshield and back window. Took bad advice on those. I have a swap kit from TCI with a stage 2 trans with wide bands and a 6th set of clutch packs on low, but concerned if something is left off my list for the conversion. I don’t have a lot of space to do the swap so I envision it without a catch. Is there a go by list for these conversions?