Yes, you have to change the motor mounts and transmission.
3.0l Vulcan engine(in rangers) has a unique bolt pattern for the transmission so you can't swap to any other engine size without also swapping the transmission.
You also need a 4.0l wiring harness and computer if that is what you use.
And frankly it wouldn't be a good swap even if it was easier.
2000 3.0l has 150 horse power
1990-2000 4.0l has 160 horse power
So only a 10 horse power gain, 6% increase in power
It would be better to just get another 3.0l, get it all running well and sell that ranger and buy one with a 4.0l.
OR............put in a 302(5.0l) V8, same amount of work as a 4.0l swap but with way more horse power, 215 horse power, 43% increase in horse power