pat I see your post is a couple years old, If you are around the forum and still have 122 parts feel free to contact me.
I have had a 1966 122 since 1985 and love the thing, I recently bought another, this second one , also 1966 has the borg warner 3 speed automatic, it has sat for many years, so its a bit rough but only has 65,000 miles on it !
The whole thing deserves a ressurection, I'll try the auto transmission but in my other I went from the OEM 4 speed to an overdrive transmission.
now you mentioned the OD trans you havei sfrom a P1800, I believe it will be comatible with my 122. The P1800 does have a different top and the shifter location is different as a result
I have other 4 speed transmissions around including the one for a 1800 but they are 4 speed ones.
the overdrive also requires a shortened driveshaft, They have two driveshafts with 3 U jounts and a center bearing. In mine I cut and welded and had it balanced to shorten it but if you have the short driveshaft I'd keep it with the transmission.
I have some spare parts cars so I salvaged the pedals, and an engine with the clutch, since the auto does't have a clutch pedal or a clutch.
I believe the M41 is the overdrive one. there may be later models of transmissoion with overdrive used in 240's and such, they would be different.
the electric overdrive has its own clutch it can be shifted without using the clutch but I noramally still use the clutch just to take the load off it when shifting to overdrive.
on the right side of the sterering column there should also be a switch it matches cosmetically with the signal light switch on the left side, a button or toggle switch can be used.
I had a problem before where the solenoid for the overdrive failed , I managed to buy a spare overdrive transmision to get that, but the former owner of that one had it hooked up so it can work in any gear, normally there is a 4th gear switch so the overdrive can only be enguaged in 4th.. well if you start shifting into overdrive in a low gear or reverse bad things may happen and in this one they had sheared the whole back of the treansmission casting.
I think other than the overdrive the transmision parts are interchangeable except the M41 has an extended output shaft. this means you cannot simply bolt on the overdrive to a standard 4 speed as the standard 4 speed will not have the longer output shaft.
Im in Canada near Vancouver BC,( Canada) so Im not sure if you still have that transmission or any suspension parts etc around, If you do and feel ok making a deal I'd be happy to discuss by PM.
ill try to PM you my email adress just to alert you, in case you are interested.
the new to me 122 seems to have had shocks replaced but I want to rebuild some of the rubber bushings etc, Im fine using IPD polyurathane parts instead of OEM which are rubber.
the trans mayhave been used in other british cars such as the sunbeam tiger, but I am unfamilar with other british cars which may have used it.
some of the 122s 122 wagons used the overdrive it was an option the 123GT was special, it had the overdrive and a limited slip differential.
I found that when I went and put in an overdrive in to my stock 122 it had very high gearing, I was able to source a new crown and pinion which dropped my rear end ratio back down so it was more normal. they had a few extra cosmetic bts and were all 2 door models.
With the stock rear axle it could go 100MPH all day long but it is hard here ot find a road long and flat enough where that is practical .. the the car isn't stable at any speed over about 100 MPH. I normally only drive it up to maybe 120 K or 80 MPH or so.
if the overdrive came from a 1800 Im sure it will work in a 122 or a 1800, they two cars have different bodies but very similar drivetrains.
Most 122's had a B18 or 1800 CC engine, I bored mine to a 2 litre, the engine also came as a B20 ( 2000 cc) which was essentially the same. the B20 had a larger valve head so I used one of those. and I polished the ports and balanced it.
the stock cam in a 122 is usually a C cam but there was a D cam used in some cars, its a bit higher performance but still a stock volvo cam grind , so I used that to increase the power a bit more. all the work resulted in a car that can basically keep up with modern cars. I do like the concept of racing people who are completely unaware they are being raced ;-)
after owning my forst 122 so long I have really enjoyed it, the body on this new to me one is rough but seems ot suffer less from frame rust, Ill try to ressurect it, the interior is nice and I couldn't ask for a more original specimen.
mine are both 4 door models, the 2 doors are more commonly restored and maybe a bt higher priced, there are more 2 door models left now, but there were more 4 door models sold and they were more expensive than the 2 door. Perfomance is very similar as the weight was very similar. the 2 door is considered more "sporty."
122s were originally marketed as the "Amazon" so many will refer to them as volvo amazons. in early production the amazon name was in conflict with a bicycle manufacturer so they were actually branded as a 122 or more commonly 122S 123's are rare and sought after. the wagons are similar and nice too.
Ilike the fact that in a 122 you domt have ot lie down to drive it. you sit in a more comfortable positionbut they don't look as sporty.
I have a early sales brocure 1962, where it shows seatbelts in the front as being an option, Volvo invented the 3 point harness. Mine never had rear seat belts.
since seat belts are now written into law and you have to wear them. cars that didn't have them mean the owners have the option of not wearing their seatbelt and can do this legally. ( if they were not installed)
If I have kids in the back I need to assure they wear their seatbelt or it is illegal. Since there were none in the back, I am exempt.
I have never seen a 122 with no seatbelts in the front.
the cars were unibody so a frame off restoration is impractical, otherwise they are extremely reliable sturdy and simple cars, the fusebox and wiring is extremely basic, this new one didn't even have a radio, no 4 way flashers. no extra electrical and no electronics , I believe this simplicity added a great deal to the servicability and reliability. If its not there it can't break.
the engines are pushrod engines with an underhead cam. theyare very sturdy engines , I'd say similar of the transmissions.
the ones I have seen have all had dual HS-6 carbs, the 2 litre had a bit larger jets. there is an ID tag on the carbs which differentiates. probably a lot of british cars had similar carbs. Im not sure which ones.
This site is actually about british cars not swedish cars but there are some simiarities. hopefully others dont mind the OT post. I suspect we are probably mostly all old car nuts and have a common interest.
Hey Guest!
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
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Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
)
... That turns out to have a completely seized engine from being put away with only water in the radiator 
I haven't brought myself to list it yet. It's definitely a clean straight example.
