so correct me if Im wrong but half the fluid is in the torque converter not in the pan so if you change the pan you have just performed about half a transmission oil change, maybe 2/3.

in my 88 ford van I couldn't get that pan off. the bolts were all corroded so I gave up before having to fix stripped pan bolts. I knew if I continued I'd pull the bolt out along with the aluminum threads. maybe someone used loctite.

what I did then, was siphoned the fluid out of the dipstick with a small hose and refilled the same way , also removed the plug in the torque converter after gaining access by removing the aluminum brace thing under the bellhousing. I couldnt access the screen so I left well enough alone thare. I got some never sieze on the bolts and the stubborn ones might come loose if I try again this year. I ended up with oil that was maroon in color and refilled it. Not perfect but time was limited, and better than nothing. that pan has no plug to drin from , the volvo does.

siphoning takes time , so I just take a break and watch it until it stops. in manual transmissin cars I remember pumping from a can until my thumb was sore or running a hose out to the top of the car and rigging up a funnel on a hanging wire.

I think Volvos probably do have a drain plug on the torque converter but I don't recall ever removing one. I do recall taking apart a 140 and puled the engine then the torque converter fell out, maybe with some help, along with a gallon or two and it surprised me. I guess I had pulled the torque converter foreward with the engine removed, then sploosh !

Ive never actually flushed a transmission. maybe the easy way is to have a oil change place do it but Ive always been too cheap for that ;-) I'm not sure how much fluid you'd use to do it properly at home.

you might get a leak where the output shaft leaves the transmission to connect to the driveshaft. there is an oilseal and it's probably not that hard to change. my 740 leaks quite a bit so I have to keep picking different parking spaces to avoid being in trouble ;-) it seems to be getting worse so I could check the fluid and I need to look into changing that seal.