Re: 1978 OMC Sterndrive Volvo Penta AQ120B Replace u-joints
Some guys can change out the ujoints without taking anything else apart. When I did mine, I removed the ujoint assembly entirely to make it much easier. Here is how its removed.
http://www.volvopentastore.com/Upper-Gear-Unit-Aq-Drive-Unit-270-270t/dm/*******.055821924--**********.333958061--store_id.366--view_id.317448
Remove the 4 bolts, #38 in the link. These can be hard to remove and have been known to break or strip so use caution. My freshwater boat has very little corrosion and the bolts, while tough to break loose, all came out ok.
Once the four bolts are out, you can remove the double bearing box, still attached to the ujoints, from the upper gear box. Note, there are shims (#20) behind this that need to go back, and 2 orings (19) that will need to be replaced.
Now all you need to do is remove the bolt (#35) and the ujoint yoke will slide out of the double bearing box. Loctite the bolt when you reassemble.
I think thats it, it's been a couple years...
Let us know how it goes.