Welcome to TRS
Reads like you have more than 1 problem.
Leave engine off and transmission in Neutral, can you roll the truck by pushing it?
EDIT: sorry you said you couldn't roll it easily
Then jack up each front wheel and see if it spins.
Then jack up each rear wheel and see if it spins(transmission still in Neutral).
If a wheel doesn't spin then that brake is locked.
If no wheels spin the Master Cylinder is locked.
If all wheels spin but truck is hard to roll then could be transmission bearing is bad or rear axle bearing.
On the rear axle differential, about 3/4 of the way up, is a bolt on the cover, remove it, it is the Fill hole for axle oil, use finger or "dip stick" to get some oil out, smell it, you can tell instantly if it smells burnt, if so drain oil by removing cover and have a look inside.
On the drivers side of trans there will be a larger bolt about 1/2 way up the side of trans, remove it, this is the Fill hole to add transmission fluid, some fluid should start to leak out if trans is full.
1994 Ranger manual transmission uses ATF, yes, Automatic Transmission Fluid, in a manual transmission.
Use your finger or a "dip stick" of some sort to get a look at the transmission fluid inside, red is the color of good fluid, black is the color of burnt fluid, it will be black if a bearing is bad.
Engine overheating that fast reads like a blown head gasket.
Cold engine
Remove radiator cap
make sure there is coolant in radiator, if not add some, or some water
Start engine
Watch for coolant bubbling out of rad cap opening
If it does and continues to bubble out then you do have a blown head gasket or cracked head.
Search on this site for Glove Test
It is a free test and it will confirm bad head gasket, even ID where it is blown