You must have really hated that car for it to need a second engine
Mine hit 280+k on it's original drivetrain (second clutch).
The gearbox I kinda understand because no one services them and then wonders why they stop working after 120-150k
First engine sucked up a load of silicone and old O rings which blocked the strainer and wrecked the bottom end. This was about 3 years into me owning it, and I hadn't done any engine work on it at that point (except cam belt), so it wasn't me that put the silicone and old seals in the sump. I had changed the GB fluid and filters soon after getting it, (and put a proper spin on filter connector on the engine
). If I'd known the V6 had such a pi55 poor pickup I'd have dropped the sump to check and clean it.
Gearbox is/was an auto, and failed 18 months ago ish after about 280K miles. Spoke to a few GB reconditioners who agreed it was likely to be the seals on the hydraulic solenoid which presses the clutch plates together. If the solenoid seals leak it doesn't apply enough pressure to the plates, which start to slip more than they should, and then wear out so you're looking at quite a big bill for parts and labour to repair. Loads of stuff on Youtube about it, and perhaps I could have done it myself, but cheaper to just replace with a known good gearbox was the consensus on here and with them.
I know the popular view on here is that cam cover leaks are due to blocked breathers, but I've never found mine to be blocked, and I think that's only a symptom now, not the real cause. IMHO the real cause on older engines is excessive blowby of the piston rings caused by bore, piston and ring wear. The crank case only really needs to 'breathe' blowby - where else is high pressure air coming from? My first 3 Omegas (I've had 4) never leaked - infact I wasn't even aware that cam cover leaks were an issue. But an old engine is going to have more blowby, and that air has to escape somehow. Plastic cam covers are going to flex more than metal ones, and the more blowby there is the more air needs to escape. YMMV.