Reverse not working?

There really are no temporary fixes for that problem. That trans really has only 2 items that routinely stop reverse. The first is the sun shell (red) failing, however with that failure you also lose second and fourth gears along with reverse. The other that takes out only reverse is the reverse drum snap ring (green) failing. That can allow the symptom you have where it simply stops working and sometimes acts like it wants to engage. That is because the reverse piston will keep expanding under pressure but then it ruptures the seal, and the pressure drops, and reverse doesn't work. In both cases the only repair is to remove the transmission and take it apart to repair the parts.
Being a 2WD and the mileage you state I would actually say that a remanufactured of that unit would be good. If you have the tools, it could be rebuilt over a weekend, but you still need the parts.
You might be able to grab a used transmission from a place like a pick and pull for a temporary unit while your other one is rebuilt.

Disconnect the battery ground, then remove air cleaner assembly, then disconnect the throttle valve cable at its upper end. Now raise and support the truck so you can get under it. Now drain the fluid out of the transmission and disconnect the shift linkage.
Now disconnect the drive shaft at the rear axle and remove it from the tail shaft.
Now remove the converter support and put a jack under the transmission to support it.
Next remove the crossmember bolts and the crossmember. Now slowly lower the transmission while watching all the cables and wires so they don't stretch.
Now remove the dip stick tube and start disconnecting the wires and cables.
Disconnect the transmission cooler lines and cap them.
Remove any support braces and then the torque converter cover.
Mark the converter and flex plate so you can put them back together later. Now attach a support to the engine and remove the converter to flex plate bolts, then remove the bellhousing to engine block bolts and slide the transmission back with the converter.
Then reverse the process to install the replacement.