I have the auto transmission out in my truck. I had been told that ONLY a 98-00 4speed auto from a 4x4 would fit it. It appears the bellhousing unbolts like every other transmission I have seen and the rear spacer housing (for lack of a better term, the part the tansfercase bolts to). are removable and that other 4speed autos from say, a 2.3l non-4x4 would work with the bolt up parts. anyone know about this?
There are significant differences internally to the 4R44E/5R55E and weather or not it's a 2.3 or 3.0 and 4.0L engines. It's not as simple as changing bellhousings.
First are the bellhousings themselves. They don't interchange between the engine types for a few reasons. The way the pump supports the O/D drum is different which means it's not a simple swap.
Secondly, the planetarys are different. A 4R44E behind a 2.3L has 4 pin planetary geatsets while a 5R55E behind a 4.0l has 6 pin planetary gearsets.
Thirdly, the forward and direct clutches have less plates for the smaller engines than the 4.0L.
That said, you could take, for example, a 2002 4.0L 5R55E and swap it in place of a 98 4.0L 4R55E because the newer trans is stronger than the older. But don't swap it out the other way.