I currently have a 4.0l five speed 4x4 and would like to make it an automatic. Can someone suggest best options for this.. All help greatly appreciated.

 

You need to ID your current tranny and then go from there. A good starter source of information on that kind of swap can be found HERE.

 

Currently has fm146 5 speed

 

The best option would be to locate a donor 93 Ranger 4.0L with 4x4 and an A4LD transmission. That would give you the flex plate, torque convertor, radiator and transmission cooling lines, brake pedal assembly, shift mechanism, ECM module. I would look for one with a manual shift transfer case but electric shift transfer case could be made to work.

 

Would a transmission from a 3.0 work

 

It would be the same transmission, but by 93-94 era Ford finally started to figure out that they needed to beef it up some to handle the torque of the 4.0. Even then the A4LD just didn't live long behind the bigger V6. What year is your truck?

 

The donor transmission must be from a 4.0L to match the rear face of block/front face of transmission bolt pattern.

 

No, it doesn't. The FM146 was NEVER available behind a 4.0, and it was discontinued in 1992. You have a Mazda M5OD, which is the only manual trans to ever be offered behind a 4.0.

If you want an automatic trans, you need an auto from behind another 4.0. Any other transmission has either a different bellhousing bolt pattern (3.0 has different bellhousing pattern) or it's too weak to stand up to the 4.0's torque (any transmisison that was behind a 2.8 or 2.9 V6)

The only automatics ever offered behind a 4.0 were the A4LD, the 4r55e, and 5r55e. The A4LD is what a 1993 Ranger would've come with and would be easiest to swap in. The 4r55e and 5r55e are completely computer controlled and would require significant wiring to make work. (Someone actually did convert an Explorer from an A4LD to 5r55e; you can read about it here to see what's involved: One Way to Save a First Gen: A4LD to 5R55E Swap (Completed) | Ford Explorer and Ford Ranger Forums - Serious Explorations ) You would need to do pretty much exactly what that guy did to make one of those work in your truck. Swapping in an A4LD would also require some wiring work, although it shouldn't be nearly as much as a 4r/5r55e.

Rangers with 4.0 and A4LD combination were offered from 1990-1994. You can also find them in Explorers and Mazda Navajos 1991-1994.

You also need to find one from a 4x4 truck. 2wd transmissions have a different output shaft and tailhousing. Trying to convert a 2wd trans to a 4x4 trans (swapping out the output shaft) requires disassembling the whole transmission. Although you'd be looking for a transmission that's between 22 and 26 years old, so a rebuild wouldn't be a bad idea before installing anyway.