When I bought my '75 CJ5 I went to change the oil filter and found the motor mount was embedded in the side of it. I used a screwdriver and between the motor mount acting like a can opener and the holes the screwdriver was putting in it had pretty well removed the end of the filter before I got it off. Of course by that time it had no oil in it, but it was still the heaviest oil filter I've ever handled. I'm thinking the PO had avoided that job for a long time
On the AMC 258 six the oil filter is on the passenger side, directly above the motor mount. Years of oil running down onto the rubber mount every time the filter was changed had softened the rubber significantly, allowing the engine to settle to the point where the oil filter was pressed against the mount. I replaced the motor mount and put a remote-mount filter on it to get the oil spills away from the motor mount.
On the chain trick, I haven't seen that. But I have seen and used chain Vice-Grips which do pretty much the same thing. But this is a clever way to do the same thing, probably in less space and with the tools at hand.
Bob
Sorry, no '80 - '86 Ford trucks
"Oswald": 1997 F-250HD crew cab short box, 460, E4OD, 4.10 gears
"Pluto": 1971 Bronco, 302, NV3550 5 speed, Atlas 4.3:1 transfer case, 33" tires
"the motorhome": 2015 E-450-based 28' class C motorhome, 6.8L V-10
"the Dodge": 2007 Dodge 2500, 6.7L Cummins