Will a 4.0 engine from a 2004 ford ranger fit in a 1990 ford ranger that has a 4.o engine in it.
Thank You

 

Yes it physically will fit.

Motor mounts and transmissions are the same, but the engines are not
1990-2000 Rangers had 4.0l OHV engine
2001-2012 Rangers had 4.0l SOHC engine
Out side of the motor mount positions and transmission bolt pattern they have nothing else in common

Wiring and computer from 1990 won't work
Exhaust and fuel pump won't either

Not a good swap, possible just not a good swap
Rebuilding current 4.0l OHV or replacing with another 4.0l OHV would be a better swap
Or go all out and put in a 5.0l V8