4.0 Blocks

[truckerdawg]

So, I am wanting to do the "swap out the 2.9 for the 4.0" in my Bronco II. I have the 5 spd tranny. My question is concerning block casting numbers for the early 4.0. It seems there is the 90TM and the 90TM-AB. One relates to manual trannies and the other to automatics. What the heck? I can understand perhaps different harmonic balancers if the two flywheels are different weighted. So, I can get a 4.0 from an automatic donor vehicle or not? Will the whole thing bolt up correctly-is there something about the crank that won't accept manual flywheel-clutch parts? I ask because every place I looked for 90-94 remanufactured engines the two engines are separated by manual or automatic transmission and then do give the different block casting numbers. Thanks, this is the first time I have ever encountered such.

 

[trail B2]

People routinely switch from autos to manuals and nobody changes blocks.The only real surprise is they run better when you switch EEC or computer.If you search there is a ton of stuff here on this.

 

[truckerdawg]

Thank you. What you said makes sense from what I have read. I just wanted to make sure.