I read this thread when I discovered my severe oil leak was from adapter. Thanks to all for input. I did this job myself in driveway. Here's my two cents:
Did not drain oil - had to add so often, it wasn't bad. Took off filter, took out oil press sending unit, took off left front wheel, turn wheels hard to right. (do this first while engine can still run) Drained coolant. Removed four bolts - 13mm.
you will need an assortment of extensions, swivels, but it can be done. My 250 had OEM clamps on lower rad hose and there was no way the one where hose connects to neck on filter adapter could be released. So I took the hose and adapter out all connected. I popped two front pins holding inner fender plastic loose so I could reach to lower rad hose at radiator. I split the air cleaner and moved the engine half away to get to clamp under resevoir) I pulled the hose and adapter out through inner fender area near radiator. cleaned adapter well, got gkt at Oreily's $12 and a lower hose $45 and civilized clamps and it went together well. took me about 5 hours total but was not rushing. hope this helps someone else.

 

I did mine last night started at 5pm done and running at 615pm. Email or text me for helpfull tips.8137359097 Jack

 

Can I just use RTV on the part that is bolted to the engine, instead of buying a new gasket?

 

Use a gasket, do the job right.

 

That's right the 4x4's are a lot harder to change. It can be done. Remove filter and black plastic splash shield first (2 small bolts). Drain coolant. Take lower radiator hose completely off from housing and radiator and set it aside. Remove top hose at reservoir only. I used a two foot long 3/8 extension with a 10mm shallow impact swivel coming up on front side of rack and pinion to get front bolts and rear side of rack to get rear bolts off. Make sure your on the bolt head good and using a ratchet only! break'em loose. Drop housing and rotate to unplug sensor. Then snake housing with reservoir hose still connected down through front and out. At that time you can properly clean all sealing surfaces on the block and housing to ensure a clean seal when you reinstall in the reverse order. I did the repair on a lift which made it easier. I did NOT remove P/S pump. I did remove left front tire. Not necessary to remove inner wheel well.