-voice of doom warning-
What is your daily driver?
If I were you, I would get a tow dolly, drive out there, check the rear wheel bearings on the 240, drive the 240 up on the dolly, disconnect the driveshaft, and tow it home.
Then I would repair the problem with the transmission at my leisure, rather than take a known questionable transmission over the rockies in an unknown vehicle.
There is nothing like a fun road trip in an untested car, but a transmission issue is only the beginning of all the little things that could be wrong with an older vehicle. Might be easy to fix, but better to find that out at your house or nearby than on a grade in heavy traffic 100 miles from anywhere.