4.0 Flywheel/Starter Question

[Diggerauditor]

I have a 88 2WD with a 2.9. I'm swapping in a 4.0. My 2.9 is 5-spd but most of the 4.0's around here are auto. Will the 2.9 flywheel fit or do I need to find a 4.0 flywheel/starter?

 

[AllanD]

the 2.9 starter will not fit the 4.0 block,

The mounting bolt pattern is the same, but the body diameter of the
2.9 starter is too fat to clear the reinforcing ribs on the 4.0 block.

the

Generally speaking, you don't want to run a 4.0 engine with
the lighter flywheel of a 2.9, additionally the smaller 8-7/8" clutch
used on the 2.9 is only marginally adequate for a 2.9.

The heavier flywheel and larger clutch of the 4.0 is a popular upgrade for 2.9's but absolutely mandatory for the 4.0.

AD