C6 to AOD!!!

I think I got a great deal today.  AOD transmission and torque converter for $100.  So, aside from a yoke for the driveshaft and flex plate, what else do I need to find?  Will I have to shorten or lengthen my divested?  Who's done this swap?

The driveshaft length is fine.

You need the AOD kickdown linkage or an aftermarket setup like Lokar.
TV adjustment is critical to longevity because they don't use a vacuum modulator the same way a C4 or 6 do.

One big item, what engine do you have? AOD is good on a 302, there was one offered behind a 351W and also a 300. Neither held up very well. The 351 version had more clutch discs and I believe I remember a bigger OD servo and band (I had one years ago for a project that never got built so I sold it).

I have done this swap multiple times and do this regularly. I also rebuild aods and do modifications too. the biggest issue to be concerned with is mis matching the parts. next to that you need to set up the throttle valve cable properly or the trans could be short lived. the greatest reason to do this swap is the potential of fuel economy (haha). but this also opens up the mis matched parts again. please consider the whole package as many things will be affected.

Currently considering this same swap behind a 300-6.
The information above definitely supports what I've learned over the years.
The OD servo and band do not take big power unless you build them for it.
The TV (throttle valve) adjustment is absolutely critical and really can't be done by counting threads on the cable adjuster as I've read on social media. It should be done with an actual pressure gauge and within the spec provided for that transmission.
 If you want to go deep into AODs check this guy out. His valve bodies are the best.
http://http://www.silverfoxtrans.com/index.html

good bit of info. yes silver fox is good research.
something that I always do is I consider the whole package. every time that you alter one part of this machine you inadvertently alter another also. nowhere as much as gearing. and never forget that when you change the tire diameter you are changing the gearing!
currently I am doing this with a car that is a barn find brought to us to "resurrect". the c4 is coming out and an aod is going in. now I need to explain why the rear axle needs to be dealt with too. if the axle stays as it is and the aod goes in, the cruise rpm will be too low by a long way.

As a driver a of an AOD/300 combo, some other info:

I initially set my TV cable the "factory" way, which is bringing the throttle all the way back (which since I have EEC-IV, means running a KOEO test to retract the kicker motor first) and then adjusting the cable to a "no slack" condition. From there, I adjusted it so it wasn't as likely to lug when in OD and under cruise but not so tight that it'd frequently "hang" in 3rd gear (it still does occasionally, a throttle kick or a quick shift to drive back to OD clears the hang condition). It's better to be too tight than too loose (low pressure is what kills these, the internal pressure regulator runs direct from the TV cable and is proportional to cable pull).

If you have 3.08 gears like I do (especially running 235/75R15 tires!), it will be a bit of a dog. Fuel efficient, to a point, yes. But at highway speeds it does take some knowledge of how it works to effectively drive it (to the point of almost being semi-automatic). I've toyed with swapping to 3.55's for drivability reasons, but I'm not inclined to fix what ain't broke in this case.

If you have the transmission out, do yourself a favor and swap the inner input shaft for a hardened one. They are the weakest link in the setup.

Some technical info on how it works (mainly, the split torque feature of 3rd gear): https://ateupwithmotor.com/terms-technology-definitions/split-torque-lockup-converters/6/

Finally, if you're towing anything of any significant load, stay out of OD. Due to the dual input shaft design, 3rd gear uses both shafts to transfer torque; OD only uses the inner shaft (direct-drive), which is a recipe for twisting the end of the shaft off (hardened shafts supposedly help, but still not advised for towing!).